Péter Kós | Biological Research Centre of Hungarian Academy of Sciences (original) (raw)

Papers by Péter Kós

Archives of Virology, 2005

Barley mild mosaic virus (BaMMV), a member of the family Potyviridae, genus Bymovirus, is involve... more Barley mild mosaic virus (BaMMV), a member of the family Potyviridae, genus Bymovirus, is involved in the economically important yellow mosaic disease of winter barley in East Asia and Europe. We investigated serological properties of bacterially expressed BaMMV coat protein (CP) of a German isolate. Ten mouse monoclonal antibodies were produced using purified E. coli expressed BaMMV-CP as immunogen. The reactivity of MAbs with different strains of BaMMV was analysed by several immunological methods that are frequently used in diagnostic virology: enzyme-linked immunosorbent assay (ELISA), dotblot, Western-blotting (WB), direct tissue blotting immunoassay (DTBIA) and immunoelectron microscopy (IEM). The amino acids involved in the formation of epitopes recognised by several MAbs were mapped by using synthetic pin-bound peptides and the localisation of epitopes in assembled virus particles was determined by electron microscope studies. MAbs V29 and M1 decorated the whole virion indicating that their epitopes 6 PDPI 9 and 96 ITDDEK 101 , respectively, are exposed on the surface. The MAbs V6 and V14 both interacted with 44 LPEPKM 49 , which seems to be accessible at only one end of the virus particle. The MAbs V6, V14, V29 and M1 detected epitopes common to a wide range of BaMMV isolates and can therefore be used effectively in routine diagnostic tests for BaMMV from barley leaves. We suggest that MAbs M1, V6, V14 and V29 are most suitable for use in TAS-ELISA, V6, V14 and V29 for Western blotting and V29 and M1 for electron microscope serology.

Environmental Engineering and Management Journal

In the present study the potential of a gene fusion between the arsB promoter from Synechocystis ... more In the present study the potential of a gene fusion between the arsB promoter from Synechocystis 6803 and the bacterial luxAB genes was evaluated to be used as a cyanobacterial bioreporter for monitoring the bioavailability of inorganic arsenic species. A whole-cell bioreporter strain, designated arsLux, was constructed based on this fusion. In concert with the specificity of the promoter presented earlier, luminescent signal could be detected upon exposure to arsenite, arsenate and antimonite, in a concentration-dependent manner, following an incubation period of 14 hours. The detection range of arsLux was 4 μM to 1 mM for As(III) and Sb(III), and 150 μM to 150 mM for As(V). However, arsLux activity was inhibited by Cu 2+ and Zn 2+ with a half maximal inhibitory concentration (IC50) of about 8 μM and 16 μM, respectively. The bioreporter performance was tested using water samples from a thermal spring and from the River Tisza, both of them supplemented with arsenite. In the first case the bioluminescent signal was comparable with the signal of the standard solution, whereas in the second case the signal was much lower, presumably due to inhibitors present in the river water. Our data show the arsB promoter has the potential for whole cell bioreporter applications with some further improvements that are also discussed.

Applied microbiology and biotechnology, Jan 21, 2018

Sulfide detoxification can be catalyzed by ancient membrane-bound flavoproteins, sulfide:quinone ... more Sulfide detoxification can be catalyzed by ancient membrane-bound flavoproteins, sulfide:quinone oxidoreductases (Sqr), which have important roles in sulfide homeostasis and sulfide-dependent energy conservation processes by transferring electrons from sulfide to respiratory or photosynthetic membrane electron flow. Sqr enzymes have been categorized into six groups. Several members of the groups I, II, III, and V are well-known, but type IV and VI Sqrs are, as yet, uncharacterized or hardly characterized at all. Here, we report detailed characterization of a type VI sulfide:quinone oxidoreductase (TrSqrF) from a purple sulfur bacterium, Thiocapsa roseopersicina. Phylogenetic analysis classified this enzyme in a special group composed of SqrFs of endosymbionts, while a weaker relationship could be observed with SqrF of Chlorobaculum tepidum which is the only type VI enzyme characterized so far. Directed mutagenesis experiments showed that TrSqrF contributed substantially to the sulfi...

Applied microbiology and biotechnology, Jan 19, 2017

Novosphingobium resinovorum SA1 was the first single isolate capable of degrading sulfanilic acid... more Novosphingobium resinovorum SA1 was the first single isolate capable of degrading sulfanilic acid, a widely used representative of sulfonated aromatic compounds. The genome of the strain was recently sequenced, and here, we present whole-cell transcriptome analyses of cells exposed to sulfanilic acid as compared to cells grown on glucose. The comparison of the transcript profiles suggested that the primary impact of sulfanilic acid on the cell transcriptome was a starvation-like effect. The genes of the peripheral, central, and common pathways of sulfanilic acid biodegradation had distinct transcript profiles. The peripheral genes located on a plasmid had very high basal expressions which were hardly upregulated by sulfanilic acid. The genomic context and the codon usage preference of these genes suggested that they were acquired by horizontal gene transfer. The genes of the central pathways were remarkably inducible by sulfanilic acid indicating the presence of a substrate-specific...

Advanced Topics in Science and Technology in China, 2013

Photosynthesis. Energy from the Sun, 2008

Page 1. Light Induced Exchange of Different psbA Gene Copies in the Cyanobacterium Thermosynechoc... more Page 1. Light Induced Exchange of Different psbA Gene Copies in the Cyanobacterium Thermosynechococcus elongatus Péter B. Kós, Zsuzsanna Deák, Otilia Cheregi, and Imre Vass Abstract The D1 subunit of the Photosystem ...

Virus Genes, 2006

Double-stranded RNAs (dsRNAs) were detected in different pine populations in Germany and Hungary.... more Double-stranded RNAs (dsRNAs) were detected in different pine populations in Germany and Hungary. Two dsRNA species of 1.5 and 1.58 kbp, respectively, persisted in the same trees for at least 2 years and their presence was not associated with any symptoms. The dsRNAs were found to sediment in the VLP (virus-like particles) fraction and to be protected by protein(s) against RNase A digestion at low salt. cDNA cloning and sequencing of the smaller segment (dsRNA2) led to the identification of a putative RNA-dependent RNA-polymerase (RdRp) containing the GDD, as well as three other, conserved motifs. Sequence comparison with different RNA viruses and phylogenetic analysis indicates that the putative RdRp from pine shows highest similarity to the homologous proteins of Beet cryptic virus 3 and of a cryptic virus of Pyrus pyrifolia. On the basis of these results we suggest that the 1.5 and 1.58 kbp dsRNAs in P. sylvestris may represent the genomic segments of a new plant cryptic virus, Cryptoviruses have not yet been reported to occur in Gymnosperms.

Journal of Photochemistry and Photobiology B: Biology, 2014

The role of the Syn-CRY cryptochrome from the cyanobacterium Synechocystis sp. PCC 6803 has been ... more The role of the Syn-CRY cryptochrome from the cyanobacterium Synechocystis sp. PCC 6803 has been a subject of research for more than a decade. Recently we have shown that photolyase, showing strong homology with Syn-CRY is required for Photosystem II repair by preventing accumulation of DNA lesions under UV-B (Vass et al. 2013). Here we investigated if Syn-CRY is also involved in PSII repair, either via removal of DNA lesions or other mechanism? The Dsll1629 mutant lacking Syn-CRY lost faster the PSII activity and D1 protein during UV-B or PAR than the WT. However, no detectable damages in the genomic DNA were observed. The transcript levels of the UV-B and light stress indicator gene psbA3, encoding D1, are comparable in the two strains showing that Dsll1629 cells are not defective at the transcriptional level. Nevertheless 2D protein analysis in combination with mass spectrometry showed a decreased accumulation of several, mostly cytoplasmic, proteins including PilA1 and bicarbonate transporter SbtA. Dsll1629 cells exposed to high light also showed a limitation in de novo assembly of PSII. It is concluded that Syn-CRY is required for efficient restoration of Photosystem II activity following UV-B and PAR induced photodamage. This effect is not caused by retardation of DNA repair, instead the synthesis of new D1 (and D2) subunit(s) and/or the assembly of the Photosystem II reaction center complex is likely affected due to the lack of intracellular CO 2 , or via a so far unidentified pathway that possibly includes the PilA1 protein.

Acta microbiologica et immunologica Hungarica, 2017

Petroleum hydrocarbons and derivatives are widespread contaminants in both aquifers and soil, the... more Petroleum hydrocarbons and derivatives are widespread contaminants in both aquifers and soil, their elimination is in the primary focus of environmental studies. Microorganisms are key components in biological removal of pollutants. Strains capable to utilize hydrocarbons usually appear at the contaminated sites, but their metabolic activities are often restricted by the lack of nutrients and/or they can only utilize one or two components of a mixture. We isolated a novel Rhodococcus sp. MK1 strain capable to degrade the components of diesel oil simultaneously. The draft genome of the strain was determined and besides the chromosome, the presence of one plasmid could be revealed. Numerous routes for oxidation of aliphatic and aromatic compounds were identified. The strain was tested in ex situ applications aiming to compare alternative solutions for microbial degradation of hydrocarbons. The results of bioaugmentation and biostimulation experiments clearly demonstrated that - in cer...

Journal of Biotechnology, 2017

In the present studies, we focused on substrate specificity of tocopherol cyclase, the key enzyme... more In the present studies, we focused on substrate specificity of tocopherol cyclase, the key enzyme in the biosynthesis of the tocopherols and plastochromanol-8, the main plant lipid antioxidants, with special emphasis on the preference for tocopherols and plastochroma-nol-8 precursors, taking advantage of the recombinant enzyme originating from Arabidopsis thaliana and isolated plastoglobules, thylakoids and various model systems like micelles and thylakoids. Plastoglobules and triacylglycerol micelles were the most efficient reaction environment for the cyclase. In various investigated systems, synthesis of γ-tocopherol proceeded considerably faster than that of plastochromanol-8, probably mainly due to different localization of the corresponding substrates in the analyzed lipid structures. Moreover, our study was complemented by bioinformatics analysis of the phylogenetic relations of the cyclases and sequence motifs, crucial for the enzyme activity, were proposed. The analysis revealed also a group of tocopherol cyclase-like proteins in a number of heterotrophic bacterial species, with a conserved region common with photosynthetic organisms, that might be engaged in the catalytic activity of both groups of organisms.

Bacteriophages were first discovered in 1915 and used as antimicrobial tools since 1919. However,... more Bacteriophages were first discovered in 1915 and used as antimicrobial tools since 1919. However, the appearance of antibiotics confined their applications. Nevertheless, phage therapy entered into its renaissance in the last few years as a consequence of frequent emergence of multidrug resistance in pathogenic microbes. The developments of newer and newer antibiotics, antimicrobial agents are very expensive and time consuming processes. The phage therapy has several advantages over antibiotics: easier and cheaper to produce, the phages are versatile, new phages can be easily isolated, moreover phage mixtures, phage cocktails can also be applied. And there is no need for long medical testing. Erwiniaand Xanthomonadsare plant pathogens, Erwinia amylovorais the infecting agent causing fire blight disease of Rosaceae plants, Xanthomonadshave broader host spectra and more diverse effect. Bordetella bronchiseticais a broad host range mammalian pathogen, while Staphylococcus aureusis a ha...

In order to improve the stress tolerance of grapevine, transgenic plants were produced and regene... more In order to improve the stress tolerance of grapevine, transgenic plants were produced and regenerated from the anthers of a grapevine rootstock cultivar expressing the ferritin of Medicago sativa. Leaf disks of the plants were exposed to oxidative stress by intracel- lular ROS production using paraquat, a herbicide known to mediate superoxide radical formation in thylakoid membranes. The Medicago ferritin

Functional Plant Biology, 2007

The production of reactive oxygen species (ROS) was studied in isolated thylakoid membranes expos... more The production of reactive oxygen species (ROS) was studied in isolated thylakoid membranes exposed to 312 nm UV-B irradiation. Hydroxyl radicals ( • OH) and hydrogen peroxide were measured directly, using a newly developed method based on hydroxylation of terephthalic acid and the homovanillic acid/peroxidase assay, respectively. At the early stage of UV-B stress (doses lower than 2.0 J cm −2 ), • OH were derived from superoxide radicals via hydrogen peroxide. Production of these ROS was dependent on photosynthetic electron transport and was not exclusive to UV-B. Both ROS were found in samples exposed to the same doses of PAR, suggesting that the observed ROS are by-products of the UV-Bdriven electron transport rather than specific initiators of the UV-B-induced damage. After longer exposure of thylakoids to UV-B, leading to the inactivation of PSII centres, a small amount of • OH was still observed in thylakoids, even though no free hydrogen peroxide was detected. At this late stage of UV-B stress, • OH may also be formed by the direct cleavage of organic peroxides by UV-B. Immunodetection showed that the presence of the observed ROS alone was not sufficient to achieve the degradation of the D1 protein of PSII centres.

OTKA Kutatási …, 2010

Page 1. 1 OTKA K 49438 The role of ferritin in enhancing the stress tolerance of grapevine Closin... more Page 1. 1 OTKA K 49438 The role of ferritin in enhancing the stress tolerance of grapevine Closing report The role of ferritin in protection against conditions evoking oxidative stress was investigated and verified in transgenic grapevine plants expressing Medicago ferritin. ...

Archives of Virology, 2005

Barley mild mosaic virus (BaMMV), a member of the family Potyviridae, genus Bymovirus, is involve... more Barley mild mosaic virus (BaMMV), a member of the family Potyviridae, genus Bymovirus, is involved in the economically important yellow mosaic disease of winter barley in East Asia and Europe. We investigated serological properties of bacterially expressed BaMMV coat protein (CP) of a German isolate. Ten mouse monoclonal antibodies were produced using purified E. coli expressed BaMMV-CP as immunogen. The reactivity of MAbs with different strains of BaMMV was analysed by several immunological methods that are frequently used in diagnostic virology: enzyme-linked immunosorbent assay (ELISA), dotblot, Western-blotting (WB), direct tissue blotting immunoassay (DTBIA) and immunoelectron microscopy (IEM). The amino acids involved in the formation of epitopes recognised by several MAbs were mapped by using synthetic pin-bound peptides and the localisation of epitopes in assembled virus particles was determined by electron microscope studies. MAbs V29 and M1 decorated the whole virion indicating that their epitopes 6 PDPI 9 and 96 ITDDEK 101 , respectively, are exposed on the surface. The MAbs V6 and V14 both interacted with 44 LPEPKM 49 , which seems to be accessible at only one end of the virus particle. The MAbs V6, V14, V29 and M1 detected epitopes common to a wide range of BaMMV isolates and can therefore be used effectively in routine diagnostic tests for BaMMV from barley leaves. We suggest that MAbs M1, V6, V14 and V29 are most suitable for use in TAS-ELISA, V6, V14 and V29 for Western blotting and V29 and M1 for electron microscope serology. 2502 D. Veliceasa et al.

Analytical Biochemistry, 1995

Acta Biologica Hungarica, 2007

Aiming at developing cyanobacterial-based biosensors for heavy metal detection, expression of hea... more Aiming at developing cyanobacterial-based biosensors for heavy metal detection, expression of heavy metal inducible genes of the cyanobacterium Synechocystis PCC 6803 was investigated by quantitative RT-PCR upon 15 minutes exposure to biologically relevant concentrations of Co 2+ , Zn 2+ , Ni 2+ , Cd 2+ , Cr 6+ , As 3+ and As 5+ . The ziaA gene, which encodes a Zn 2+ -transporting P-type ATPase showed a markedly increased mRNA level after incubation with Cd 2+ and arsenic ions, besides the expected induction by Zn 2+ salts. The Co 2+ efflux system-encoding gene coaT was strongly induced by Co 2+ and Zn 2+ salts, moderately induced by As 3+ salts, and induced at a relatively low level by Cd 2+ and As 5+ ions. Expression of nrsB, which encodes a part of a putative Ni 2+ efflux system was highly induced by Ni 2+ salts and at a low extent by Co 2+ and Zn 2+ salts. The arsB gene, which encodes a putative arsenite-specific efflux pump was highly induced by As 3+ and As 5+ ions, while other metal salts provoked insignificant transcript level increase. The transcript of chrA, in spite of the high sequence similarity of its protein product with several bacterial chromate transporters, shows no induction upon Cr 6+ salt exposure. We conclude that due to the largely unspecific heavy metal response of the studied genes only nrsB and arsB are potential candidates for biosensing applications for detection of Ni 2+ and arsenic pollutants, respectively.

Damage of DNA and Photosystem-II are among the most significant effects of UV-B irradiation in ph... more Damage of DNA and Photosystem-II are among the most significant effects of UV-B irradiation in photosynthetic organisms. Both damaged DNA and Photosystem-II can be repaired, which represent important defense mechanisms against detrimental UV-B effects. Correlation of Photosystem-II damage and repair with the concurrent DNA damage and repair was investigated in the cyanobacterium Synechocystis PCC6803 using its wild type and a photolyase deficient mutant, which is unable to repair UV-B induced DNA damages. A significant amount of damaged DNA accumulated during UV-B exposure in the photolyase mutant concomitant with decreased Photosystem-II activity and D1 protein amount. The transcript level of psbA3, which is a UV-responsive copy of the psbA gene family encoding the D1 subunit of the Photosystem-II reaction center, is also decreased in the photolyase mutant. The wild-type cells, however, did not accumulate damaged DNA during UV-B exposure, suffered smaller losses of Photosystem-II activity and D1 protein, and maintained higher level of psbA3 transcripts than the photolyase mutant. It is concluded that the repair capacity of Photosystem-II depends on the ability of cells to repair UV-B-damaged DNA through maintaining the transcription of genes, which are essential for protein synthesis-dependent repair of the Photosystem-II reaction center.

Archives of Virology, 2005

Barley mild mosaic virus (BaMMV), a member of the family Potyviridae, genus Bymovirus, is involve... more Barley mild mosaic virus (BaMMV), a member of the family Potyviridae, genus Bymovirus, is involved in the economically important yellow mosaic disease of winter barley in East Asia and Europe. We investigated serological properties of bacterially expressed BaMMV coat protein (CP) of a German isolate. Ten mouse monoclonal antibodies were produced using purified E. coli expressed BaMMV-CP as immunogen. The reactivity of MAbs with different strains of BaMMV was analysed by several immunological methods that are frequently used in diagnostic virology: enzyme-linked immunosorbent assay (ELISA), dotblot, Western-blotting (WB), direct tissue blotting immunoassay (DTBIA) and immunoelectron microscopy (IEM). The amino acids involved in the formation of epitopes recognised by several MAbs were mapped by using synthetic pin-bound peptides and the localisation of epitopes in assembled virus particles was determined by electron microscope studies. MAbs V29 and M1 decorated the whole virion indicating that their epitopes 6 PDPI 9 and 96 ITDDEK 101 , respectively, are exposed on the surface. The MAbs V6 and V14 both interacted with 44 LPEPKM 49 , which seems to be accessible at only one end of the virus particle. The MAbs V6, V14, V29 and M1 detected epitopes common to a wide range of BaMMV isolates and can therefore be used effectively in routine diagnostic tests for BaMMV from barley leaves. We suggest that MAbs M1, V6, V14 and V29 are most suitable for use in TAS-ELISA, V6, V14 and V29 for Western blotting and V29 and M1 for electron microscope serology.

Environmental Engineering and Management Journal

In the present study the potential of a gene fusion between the arsB promoter from Synechocystis ... more In the present study the potential of a gene fusion between the arsB promoter from Synechocystis 6803 and the bacterial luxAB genes was evaluated to be used as a cyanobacterial bioreporter for monitoring the bioavailability of inorganic arsenic species. A whole-cell bioreporter strain, designated arsLux, was constructed based on this fusion. In concert with the specificity of the promoter presented earlier, luminescent signal could be detected upon exposure to arsenite, arsenate and antimonite, in a concentration-dependent manner, following an incubation period of 14 hours. The detection range of arsLux was 4 μM to 1 mM for As(III) and Sb(III), and 150 μM to 150 mM for As(V). However, arsLux activity was inhibited by Cu 2+ and Zn 2+ with a half maximal inhibitory concentration (IC50) of about 8 μM and 16 μM, respectively. The bioreporter performance was tested using water samples from a thermal spring and from the River Tisza, both of them supplemented with arsenite. In the first case the bioluminescent signal was comparable with the signal of the standard solution, whereas in the second case the signal was much lower, presumably due to inhibitors present in the river water. Our data show the arsB promoter has the potential for whole cell bioreporter applications with some further improvements that are also discussed.

Applied microbiology and biotechnology, Jan 21, 2018

Sulfide detoxification can be catalyzed by ancient membrane-bound flavoproteins, sulfide:quinone ... more Sulfide detoxification can be catalyzed by ancient membrane-bound flavoproteins, sulfide:quinone oxidoreductases (Sqr), which have important roles in sulfide homeostasis and sulfide-dependent energy conservation processes by transferring electrons from sulfide to respiratory or photosynthetic membrane electron flow. Sqr enzymes have been categorized into six groups. Several members of the groups I, II, III, and V are well-known, but type IV and VI Sqrs are, as yet, uncharacterized or hardly characterized at all. Here, we report detailed characterization of a type VI sulfide:quinone oxidoreductase (TrSqrF) from a purple sulfur bacterium, Thiocapsa roseopersicina. Phylogenetic analysis classified this enzyme in a special group composed of SqrFs of endosymbionts, while a weaker relationship could be observed with SqrF of Chlorobaculum tepidum which is the only type VI enzyme characterized so far. Directed mutagenesis experiments showed that TrSqrF contributed substantially to the sulfi...

Applied microbiology and biotechnology, Jan 19, 2017

Novosphingobium resinovorum SA1 was the first single isolate capable of degrading sulfanilic acid... more Novosphingobium resinovorum SA1 was the first single isolate capable of degrading sulfanilic acid, a widely used representative of sulfonated aromatic compounds. The genome of the strain was recently sequenced, and here, we present whole-cell transcriptome analyses of cells exposed to sulfanilic acid as compared to cells grown on glucose. The comparison of the transcript profiles suggested that the primary impact of sulfanilic acid on the cell transcriptome was a starvation-like effect. The genes of the peripheral, central, and common pathways of sulfanilic acid biodegradation had distinct transcript profiles. The peripheral genes located on a plasmid had very high basal expressions which were hardly upregulated by sulfanilic acid. The genomic context and the codon usage preference of these genes suggested that they were acquired by horizontal gene transfer. The genes of the central pathways were remarkably inducible by sulfanilic acid indicating the presence of a substrate-specific...

Advanced Topics in Science and Technology in China, 2013

Photosynthesis. Energy from the Sun, 2008

Page 1. Light Induced Exchange of Different psbA Gene Copies in the Cyanobacterium Thermosynechoc... more Page 1. Light Induced Exchange of Different psbA Gene Copies in the Cyanobacterium Thermosynechococcus elongatus Péter B. Kós, Zsuzsanna Deák, Otilia Cheregi, and Imre Vass Abstract The D1 subunit of the Photosystem ...

Virus Genes, 2006

Double-stranded RNAs (dsRNAs) were detected in different pine populations in Germany and Hungary.... more Double-stranded RNAs (dsRNAs) were detected in different pine populations in Germany and Hungary. Two dsRNA species of 1.5 and 1.58 kbp, respectively, persisted in the same trees for at least 2 years and their presence was not associated with any symptoms. The dsRNAs were found to sediment in the VLP (virus-like particles) fraction and to be protected by protein(s) against RNase A digestion at low salt. cDNA cloning and sequencing of the smaller segment (dsRNA2) led to the identification of a putative RNA-dependent RNA-polymerase (RdRp) containing the GDD, as well as three other, conserved motifs. Sequence comparison with different RNA viruses and phylogenetic analysis indicates that the putative RdRp from pine shows highest similarity to the homologous proteins of Beet cryptic virus 3 and of a cryptic virus of Pyrus pyrifolia. On the basis of these results we suggest that the 1.5 and 1.58 kbp dsRNAs in P. sylvestris may represent the genomic segments of a new plant cryptic virus, Cryptoviruses have not yet been reported to occur in Gymnosperms.

Journal of Photochemistry and Photobiology B: Biology, 2014

The role of the Syn-CRY cryptochrome from the cyanobacterium Synechocystis sp. PCC 6803 has been ... more The role of the Syn-CRY cryptochrome from the cyanobacterium Synechocystis sp. PCC 6803 has been a subject of research for more than a decade. Recently we have shown that photolyase, showing strong homology with Syn-CRY is required for Photosystem II repair by preventing accumulation of DNA lesions under UV-B (Vass et al. 2013). Here we investigated if Syn-CRY is also involved in PSII repair, either via removal of DNA lesions or other mechanism? The Dsll1629 mutant lacking Syn-CRY lost faster the PSII activity and D1 protein during UV-B or PAR than the WT. However, no detectable damages in the genomic DNA were observed. The transcript levels of the UV-B and light stress indicator gene psbA3, encoding D1, are comparable in the two strains showing that Dsll1629 cells are not defective at the transcriptional level. Nevertheless 2D protein analysis in combination with mass spectrometry showed a decreased accumulation of several, mostly cytoplasmic, proteins including PilA1 and bicarbonate transporter SbtA. Dsll1629 cells exposed to high light also showed a limitation in de novo assembly of PSII. It is concluded that Syn-CRY is required for efficient restoration of Photosystem II activity following UV-B and PAR induced photodamage. This effect is not caused by retardation of DNA repair, instead the synthesis of new D1 (and D2) subunit(s) and/or the assembly of the Photosystem II reaction center complex is likely affected due to the lack of intracellular CO 2 , or via a so far unidentified pathway that possibly includes the PilA1 protein.

Acta microbiologica et immunologica Hungarica, 2017

Petroleum hydrocarbons and derivatives are widespread contaminants in both aquifers and soil, the... more Petroleum hydrocarbons and derivatives are widespread contaminants in both aquifers and soil, their elimination is in the primary focus of environmental studies. Microorganisms are key components in biological removal of pollutants. Strains capable to utilize hydrocarbons usually appear at the contaminated sites, but their metabolic activities are often restricted by the lack of nutrients and/or they can only utilize one or two components of a mixture. We isolated a novel Rhodococcus sp. MK1 strain capable to degrade the components of diesel oil simultaneously. The draft genome of the strain was determined and besides the chromosome, the presence of one plasmid could be revealed. Numerous routes for oxidation of aliphatic and aromatic compounds were identified. The strain was tested in ex situ applications aiming to compare alternative solutions for microbial degradation of hydrocarbons. The results of bioaugmentation and biostimulation experiments clearly demonstrated that - in cer...

Journal of Biotechnology, 2017

In the present studies, we focused on substrate specificity of tocopherol cyclase, the key enzyme... more In the present studies, we focused on substrate specificity of tocopherol cyclase, the key enzyme in the biosynthesis of the tocopherols and plastochromanol-8, the main plant lipid antioxidants, with special emphasis on the preference for tocopherols and plastochroma-nol-8 precursors, taking advantage of the recombinant enzyme originating from Arabidopsis thaliana and isolated plastoglobules, thylakoids and various model systems like micelles and thylakoids. Plastoglobules and triacylglycerol micelles were the most efficient reaction environment for the cyclase. In various investigated systems, synthesis of γ-tocopherol proceeded considerably faster than that of plastochromanol-8, probably mainly due to different localization of the corresponding substrates in the analyzed lipid structures. Moreover, our study was complemented by bioinformatics analysis of the phylogenetic relations of the cyclases and sequence motifs, crucial for the enzyme activity, were proposed. The analysis revealed also a group of tocopherol cyclase-like proteins in a number of heterotrophic bacterial species, with a conserved region common with photosynthetic organisms, that might be engaged in the catalytic activity of both groups of organisms.

Bacteriophages were first discovered in 1915 and used as antimicrobial tools since 1919. However,... more Bacteriophages were first discovered in 1915 and used as antimicrobial tools since 1919. However, the appearance of antibiotics confined their applications. Nevertheless, phage therapy entered into its renaissance in the last few years as a consequence of frequent emergence of multidrug resistance in pathogenic microbes. The developments of newer and newer antibiotics, antimicrobial agents are very expensive and time consuming processes. The phage therapy has several advantages over antibiotics: easier and cheaper to produce, the phages are versatile, new phages can be easily isolated, moreover phage mixtures, phage cocktails can also be applied. And there is no need for long medical testing. Erwiniaand Xanthomonadsare plant pathogens, Erwinia amylovorais the infecting agent causing fire blight disease of Rosaceae plants, Xanthomonadshave broader host spectra and more diverse effect. Bordetella bronchiseticais a broad host range mammalian pathogen, while Staphylococcus aureusis a ha...

In order to improve the stress tolerance of grapevine, transgenic plants were produced and regene... more In order to improve the stress tolerance of grapevine, transgenic plants were produced and regenerated from the anthers of a grapevine rootstock cultivar expressing the ferritin of Medicago sativa. Leaf disks of the plants were exposed to oxidative stress by intracel- lular ROS production using paraquat, a herbicide known to mediate superoxide radical formation in thylakoid membranes. The Medicago ferritin

Functional Plant Biology, 2007

The production of reactive oxygen species (ROS) was studied in isolated thylakoid membranes expos... more The production of reactive oxygen species (ROS) was studied in isolated thylakoid membranes exposed to 312 nm UV-B irradiation. Hydroxyl radicals ( • OH) and hydrogen peroxide were measured directly, using a newly developed method based on hydroxylation of terephthalic acid and the homovanillic acid/peroxidase assay, respectively. At the early stage of UV-B stress (doses lower than 2.0 J cm −2 ), • OH were derived from superoxide radicals via hydrogen peroxide. Production of these ROS was dependent on photosynthetic electron transport and was not exclusive to UV-B. Both ROS were found in samples exposed to the same doses of PAR, suggesting that the observed ROS are by-products of the UV-Bdriven electron transport rather than specific initiators of the UV-B-induced damage. After longer exposure of thylakoids to UV-B, leading to the inactivation of PSII centres, a small amount of • OH was still observed in thylakoids, even though no free hydrogen peroxide was detected. At this late stage of UV-B stress, • OH may also be formed by the direct cleavage of organic peroxides by UV-B. Immunodetection showed that the presence of the observed ROS alone was not sufficient to achieve the degradation of the D1 protein of PSII centres.

OTKA Kutatási …, 2010

Page 1. 1 OTKA K 49438 The role of ferritin in enhancing the stress tolerance of grapevine Closin... more Page 1. 1 OTKA K 49438 The role of ferritin in enhancing the stress tolerance of grapevine Closing report The role of ferritin in protection against conditions evoking oxidative stress was investigated and verified in transgenic grapevine plants expressing Medicago ferritin. ...

Archives of Virology, 2005

Barley mild mosaic virus (BaMMV), a member of the family Potyviridae, genus Bymovirus, is involve... more Barley mild mosaic virus (BaMMV), a member of the family Potyviridae, genus Bymovirus, is involved in the economically important yellow mosaic disease of winter barley in East Asia and Europe. We investigated serological properties of bacterially expressed BaMMV coat protein (CP) of a German isolate. Ten mouse monoclonal antibodies were produced using purified E. coli expressed BaMMV-CP as immunogen. The reactivity of MAbs with different strains of BaMMV was analysed by several immunological methods that are frequently used in diagnostic virology: enzyme-linked immunosorbent assay (ELISA), dotblot, Western-blotting (WB), direct tissue blotting immunoassay (DTBIA) and immunoelectron microscopy (IEM). The amino acids involved in the formation of epitopes recognised by several MAbs were mapped by using synthetic pin-bound peptides and the localisation of epitopes in assembled virus particles was determined by electron microscope studies. MAbs V29 and M1 decorated the whole virion indicating that their epitopes 6 PDPI 9 and 96 ITDDEK 101 , respectively, are exposed on the surface. The MAbs V6 and V14 both interacted with 44 LPEPKM 49 , which seems to be accessible at only one end of the virus particle. The MAbs V6, V14, V29 and M1 detected epitopes common to a wide range of BaMMV isolates and can therefore be used effectively in routine diagnostic tests for BaMMV from barley leaves. We suggest that MAbs M1, V6, V14 and V29 are most suitable for use in TAS-ELISA, V6, V14 and V29 for Western blotting and V29 and M1 for electron microscope serology. 2502 D. Veliceasa et al.

Analytical Biochemistry, 1995

Acta Biologica Hungarica, 2007

Aiming at developing cyanobacterial-based biosensors for heavy metal detection, expression of hea... more Aiming at developing cyanobacterial-based biosensors for heavy metal detection, expression of heavy metal inducible genes of the cyanobacterium Synechocystis PCC 6803 was investigated by quantitative RT-PCR upon 15 minutes exposure to biologically relevant concentrations of Co 2+ , Zn 2+ , Ni 2+ , Cd 2+ , Cr 6+ , As 3+ and As 5+ . The ziaA gene, which encodes a Zn 2+ -transporting P-type ATPase showed a markedly increased mRNA level after incubation with Cd 2+ and arsenic ions, besides the expected induction by Zn 2+ salts. The Co 2+ efflux system-encoding gene coaT was strongly induced by Co 2+ and Zn 2+ salts, moderately induced by As 3+ salts, and induced at a relatively low level by Cd 2+ and As 5+ ions. Expression of nrsB, which encodes a part of a putative Ni 2+ efflux system was highly induced by Ni 2+ salts and at a low extent by Co 2+ and Zn 2+ salts. The arsB gene, which encodes a putative arsenite-specific efflux pump was highly induced by As 3+ and As 5+ ions, while other metal salts provoked insignificant transcript level increase. The transcript of chrA, in spite of the high sequence similarity of its protein product with several bacterial chromate transporters, shows no induction upon Cr 6+ salt exposure. We conclude that due to the largely unspecific heavy metal response of the studied genes only nrsB and arsB are potential candidates for biosensing applications for detection of Ni 2+ and arsenic pollutants, respectively.

Damage of DNA and Photosystem-II are among the most significant effects of UV-B irradiation in ph... more Damage of DNA and Photosystem-II are among the most significant effects of UV-B irradiation in photosynthetic organisms. Both damaged DNA and Photosystem-II can be repaired, which represent important defense mechanisms against detrimental UV-B effects. Correlation of Photosystem-II damage and repair with the concurrent DNA damage and repair was investigated in the cyanobacterium Synechocystis PCC6803 using its wild type and a photolyase deficient mutant, which is unable to repair UV-B induced DNA damages. A significant amount of damaged DNA accumulated during UV-B exposure in the photolyase mutant concomitant with decreased Photosystem-II activity and D1 protein amount. The transcript level of psbA3, which is a UV-responsive copy of the psbA gene family encoding the D1 subunit of the Photosystem-II reaction center, is also decreased in the photolyase mutant. The wild-type cells, however, did not accumulate damaged DNA during UV-B exposure, suffered smaller losses of Photosystem-II activity and D1 protein, and maintained higher level of psbA3 transcripts than the photolyase mutant. It is concluded that the repair capacity of Photosystem-II depends on the ability of cells to repair UV-B-damaged DNA through maintaining the transcription of genes, which are essential for protein synthesis-dependent repair of the Photosystem-II reaction center.