Krystyna Wolska - Academia.edu (original) (raw)

Papers by Krystyna Wolska

Beilstein Journal of Nanotechnology, 2020

We report on the synthesis of composite nanobeads with antibacterial properties. The particles co... more We report on the synthesis of composite nanobeads with antibacterial properties. The particles consist of polystyrene cores that are surrounded by sulfonic gel shells with embedded silver nanoparticles. The nanocomposite beads are prepared by sulfonation of polystyrene particles followed by accumulation of silver ions in the shell layer and subsequent reduction with sodium borohydride. The resulting material has been characterized by electron microscopy, vibrational and X-ray photoelectron spectroscopy and several other experimental techniques. It was shown that sodium borohydride reduces silver ions embedded in the gel layer producing silver nanoparticles but also transforms a fraction of sulfonic groups in the polymer to moieties with sulfur in a lower oxidation state, likely thiols. It is hypothesized that the generated thiol groups are anchoring the nanoparticles in the gel shell of the nanobeads stabilizing the whole structure. The silver-decorated nanobeads appear to be a prom...

Proceedings of the National Academy of Sciences, 1995

Transcription of downstream genes in the early operons of phage lambda requires a promoter-proxim... more Transcription of downstream genes in the early operons of phage lambda requires a promoter-proximal element known as nut. This site acts in cis in the form of RNA to assemble a transcription antitermination complex which is composed of lambda N protein and at least four host factors. The nut-site RNA contains a small stem-loop structure called boxB. Here, we show that boxB RNA binds to N protein with high affinity and specificity. While N binding is confined to the 5' subdomain of the stem-loop, specific N recognition relies on both an intact stem-loop structure and two critical nucleotides in the pentamer loop. Substitutions of these nucleotides affect both N binding and antitermination. Remarkably, substitutions of other loop nucleotides also diminish antitermination in vivo, yet they have no detectable effect on N binding in vitro. These 3' loop mutants fail to support antitermination in a minimal system with RNA polymerase (RNAP), N, and the host factor NusA. Furthermore...

Future microbiology, 2018

Pseudomonas aeruginosa is one of the most clinically important opportunistic pathogen in humans. ... more Pseudomonas aeruginosa is one of the most clinically important opportunistic pathogen in humans. The aim of the project was to study effects of HtpG on the selected virulence factors responsible for pathogenesis and biofilm formation of P. aeruginosa. By characterizing a htpG null mutant of P. aeruginosa, we have identified the role of HtpG in the production of selected factors. We showed that ΔhtpG mutant affects many physiological processes containing: decreased activity of the LasA protease, reduction of biofilm formation, decreased motility, and diminished amount of rhamnolipids and pyoverdine/pyocyanin. These defects were most evident when the ΔhtpG strain was cultured at 42°C. Our findings demonstrate the unexplored role of HtpG in the pathogenicity of P. aeruginosa, and indicate potential targets for antibacterial therapeutics. [Formula: see text].

Nanomedicine (London, England), May 1, 2018

To investigate the in vitro activity of silver NPs (AgNPs) against pathogenic microalgae of the P... more To investigate the in vitro activity of silver NPs (AgNPs) against pathogenic microalgae of the Prototheca genus. The antialgal potential of AgNPs against Prototheca species of both clinical and environmental origin was assessed from minimum inhibitory (algistatic) and algicidal concentrations. The in vitro cytotoxicity of AgNPs against bovine mammary epithelial cell line was evaluated by means of the standard MTT assay. AgNPs showed a strong killing activity toward Prototheca algae, as the minimal algicidal concentration (MAC) values matched perfectly the corresponding minimum inhibitory concentration (MIC) values for all species (MAC = MIC, 1-4 mg/l), except P. stagnora (MIC > 8 mg/l). The concentrations inhibitory to pathogenic Prototheca spp. (MIC, 1-4 mg/l) were below the concentrations at which any toxicity in epithelial cells could be observed (CC > 6 mg/l). The study emphasizes the potential of AgNPs as a new therapeutic tool for the management of Prototheca infections.

Bacteriophage X N gene product acts to modify host RNA polymerase allowing the formation of a ter... more Bacteriophage X N gene product acts to modify host RNA polymerase allowing the formation of a termination-resistant transcription apparatus. Previous studies have demonstrated that the nusE71 mutation that has altered the ribosomal protein S10 prevents N action in vivo. Using a coupled transcription-translation system, we demonstrate here that purified S10 protein as well as the 30S ribosomal subunit is sufficient to restore N activity in the nusE mutant extract, allowing antitermination of Rho-dependent and Rho-independent terminators. This provides direct biochemical evidence that the S10 protein itself is one of the cellular components necessary for the formation of an antitermination apparatus. The N gene product of bacteriophage X acts to suppress transcription termination in Escherichia coli (1-5). The action ofN depends on a recognition site (nut) encoded by the phage genome (6-9). It is thought that N acts to modify RNA polymerase at the nut site, allowing the formation of a...

Polish journal of microbiology / Polskie Towarzystwo Mikrobiologów = The Polish Society of Microbiologists, 2004

The content of fatty acids extracted from the membranes of E. coli MC 1061 harboring the wild-typ... more The content of fatty acids extracted from the membranes of E. coli MC 1061 harboring the wild-type dnaKdnaJ alleles and its delta dnaJ and delta dnaKdnaJ derivatives was compared. It was demonstrated that dodecanoic acid was missing in NPLs fraction extracted from both mutants grown at 42 degrees C. Phospholipids extracted from mutant strains were deprived of hexadecanoic acid methyl ester and octadecanol, the latter being correlated with the presence of octadecanoic acid. The amount of LPS extracted from delta dnaKdanJ mutant was significantly lower when compared with wild-type strain and delta dnaJ mutant.

Acta of bioengineering and biomechanics, 2016

The aim of the paper was to investigate the antifungal activity of zinc oxide nanoparticles (ZnON... more The aim of the paper was to investigate the antifungal activity of zinc oxide nanoparticles (ZnONPs) against Candida albicans. Some attempts have been made to find out the best way to introduce ZnONPs into polymethyl methacrylate (PMMA) resin material and to determine some parameters of a newly formed composite. Zinc oxide nanoparticles were manufactured and their basic physical parameters were determined (average particle size, density, specific surface area). Minimal inhibitory concentration (MIC) of ZnONPs was determined for the Candida albicans standard strain. The average size of ZnO conglomerates in the monomer solution of PMMA resin was measured using a dynamic light scattering instrument. PMMA resin samples with incorporated ZnONPs were produced. The morphology of nanopowder and the newly formed composite was examined under a scanning electron microscope (SEM). In addition, the roughness parameter of PMMA resin material was investigated before and after ZnONPs modification. ...

Acta Microbiologica Polonica, Feb 1, 2003

In the environment horizontal DNA transfer between various bacterial species and genera takes pla... more In the environment horizontal DNA transfer between various bacterial species and genera takes place by transformation, transduction, but mainly by conjugation. Conjugation is responsible for the spread of genes coding for antibiotic resistance and xenobiotic degradation. Transfer events are reported in animal, rhizosphere and phylloplane ecosystems and in non polluted and polluted water and soil. Genetic exchange between Bacteria and Archaea is also observed. Evaluation of the extent of interspecies gene transfer is crucial in view of the deliberate release of a variety of unmodified and genetically modified microorganisms into the natural environments.

Acta Microbiologica Polonica, Feb 1, 2002

Escherichia coli null dnaJ and dnaKdnaJ mutants, when introduced to Hfr donor, impair its ability... more Escherichia coli null dnaJ and dnaKdnaJ mutants, when introduced to Hfr donor, impair its ability to DNA transfer during conjugation. The additive effect of both mutations was shown. Lack of DnaK and DnaJ chaperones also decrease the extent of proteolysis in mutant strains. This effect is seen only at 42 degrees C. The influence of double dnaKdnaJ deletion but not single dnaJ deletion on novobiocin susceptibility was also demonstrated.

Folia Microbiol Prague, 2002

The effect of mutations in dnaK and dnaJ genes on the expression of two operons that are part of ... more The effect of mutations in dnaK and dnaJ genes on the expression of two operons that are part of cysteine regulon was determined using Escherichia coli strains harboring cysPTWA::lacZ and cysJIH::lacZ fusions. Null dnaJ and dnaKdnaJ mutants were impaired in [3-galactosidase expression from both fusions. Efficient complementation of this defect by wild-type alleles present on a low-copy number plasmid was achieved. The presence of the pMH224 plasmid coding for CysB* protein defective in DNA binding lowered [3-galactosidase expression from cysPTWA::lacZ fusion strain harboring wild-type dnaKdnaJ alleles but did not diminish enzyme expression in AdnaJ and AdnaKdnaJ strains.

Cell stress & chaperones, 2015

The bacterial chaperone high-temperature protein G (HtpG), a member of the Hsp90 protein family, ... more The bacterial chaperone high-temperature protein G (HtpG), a member of the Hsp90 protein family, is involved in the protection of cells against a variety of environmental stresses. The ability of HtpG to form complexes with other bacterial proteins, especially those involved in fundamental functions, is indicative of its cellular role. An interaction between HtpG and DnaA, the main initiator of DNA replication, was studied both in vivo, using a bacterial two-hybrid system, and in vitro with a modified pull-down assay and by chemical cross-linking. In vivo, this interaction was demonstrated only when htpG was expressed from a high copy number plasmid. Both in vitro assays confirmed HtpG-DnaA interactions.

Polish journal of microbiology / Polskie Towarzystwo Mikrobiologów = The Polish Society of Microbiologists, 2015

DnaJ chaperone, a member of the so called DnaK-DnaJ-GrpE chaperone machine plays an important rol... more DnaJ chaperone, a member of the so called DnaK-DnaJ-GrpE chaperone machine plays an important role in cell physiology. The ability of Escherichia coli ΔdnaJ mutant to form biofilm was studied. It was shown that this mutant is impaired in biofilm development when exposed to 42 degrees C for 2 h. The impairment in biofilm development was observed when the heat shock was applied either at the onset of biofilm formation or 2 h later. The biofilm formed was thinner and its structure was changed as compared to wild-type strain. This defect could be complemented by the introduction of a wild-type gene on a low-copy plasmid.

Journal of Applied Genetics, 2015

Nearly all bacterial species, including pathogens, have the ability to form biofilms. Biofilms ar... more Nearly all bacterial species, including pathogens, have the ability to form biofilms. Biofilms are defined as structured ecosystems in which microbes are attached to surfaces and embedded in a matrix composed of polysaccharides, eDNA, and proteins, and their development is a multistep process. Bacterial biofilms constitute a large medical problem due to their extremely high resistance to various types of therapeutics, including conventional antibiotics. Several environmental and genetic signals control every step of biofilm development and dispersal. From among the latter, quorum sensing, cyclic diguanosine-5'-monophosphate, and small RNAs are considered as the main regulators. The present review describes the control role of these three regulators in the life cycles of biofilms built by Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella enterica serovar Typhimurium, and Vibrio cholerae. The interconnections between their activities are shown. Compounds and strategies which target the activity of these regulators, mainly quorum sensing inhibitors, and their potential role in therapy are also assessed.

Methods in Enzymology, 1996

... Asis Das, Mahadeb Pal, Jaime Garcia Mena, William Whalen, Krystyna Wolska, Robin Crossley, Wi... more ... Asis Das, Mahadeb Pal, Jaime Garcia Mena, William Whalen, Krystyna Wolska, Robin Crossley, William Rees, Peter H. von Hippel, Nina Costantino, Donald Court, Marie Mazzulla, Amanda S. Altieri, R.Andrew Byrd, Samit Chattopadhyay, Joseph DeVito and Balaram Ghosh. ...

Acta microbiologica Polonica

RNA-dependent ATPase activity of Rho + and two mutant proteins Rho15 and Rho301 was studied. It w... more RNA-dependent ATPase activity of Rho + and two mutant proteins Rho15 and Rho301 was studied. It was shown that monomeric Rho forms oligomers in the presence of ATP. This ATP-induced structural change of Rho allows protection of the protein from heat inactivation. Poly(C), which highly activates Rho ATPase, was found to potentiate heat inactivation of Rho301, but no Rho + and Rho15, only under optimal conditions of ATP hydrolysis. It was also shown that Rho301 is defective in interaction with RNA. The molecular model postulating that Rho-catalysed ATP hydrolysis with free RNA involves the cyclic process of protein dissociation and reassembly is postulated.

Proceedings of the National Academy of Sciences, 1985

Bacteriophage X N gene product acts to modify host RNA polymerase allowing the formation of a ter... more Bacteriophage X N gene product acts to modify host RNA polymerase allowing the formation of a termination-resistant transcription apparatus. Previous studies have demonstrated that the nusE71 mutation that has altered the ribosomal protein S10 prevents N action in vivo. Using a coupled transcription-translation system, we demonstrate here that purified S10 protein as well as the 30S ribosomal subunit is sufficient to restore N activity in the nusE mutant extract, allowing antitermination of Rho-dependent and Rho-independent terminators. This provides direct biochemical evidence that the S10 protein itself is one of the cellular components necessary for the formation of an antitermination apparatus.

Acta microbiologica Polonica

Temperature sensitive dnaA recipient crossed at the restrictive temperature with HfrH, free from ... more Temperature sensitive dnaA recipient crossed at the restrictive temperature with HfrH, free from contaminating F+ cells, forms recombinants almost as proficiently as at the permissive temperature. The merozygotes are able to synthesize DNA at 42 degrees C, although the recipient and donor cells do not incorporate 3H-thymine. A substantial fraction of Lac+ recombinants, irrespective of the mating temperature, is temperature resistant (42 C-R); 15% from among those mated at 35 C and 30% from those mated at 42 C. The presence of dnaA mutation in these Lac+ 42 C-R recombinants was ascertained by co-transduction with ilv. Cell division at 42 C is inhibited in the Lac 42 C-R recombinants by acridine orange. The presence of F factor DNA in these recombinants was demonstrated directly by DNA: DNA hybridization. Suppression of dnaA mutation in Lac+ 42 degrees C-R recombinants and their sensitivity to acridine orange at 42 degrees C suggests that at least part of the F factor is integrated in...

Cell, 1984

Employing specifically engineered plasmids in which the expression of E. coli galK cistron is reg... more Employing specifically engineered plasmids in which the expression of E. coli galK cistron is regulated by transcription termination, we have analyzed the antitermination function of phage X N gene product in S30 extracts. Antitermination by N, dependent on its site of action, nut& is defective in the extracts prepared from nusA, n&3, and nusE mutants. By complementation analysis, we demonstrate that none of the these nus mutations affects the synthesis of N or the other nus gene products to cause a defect in antiterminatlon. Rather, these mutations have inactivated a set of specific host components, the Nus factors, which are essential for N activity. Curiously, an appreciable portion of N and Nus complementation activities of an S30 extract is ribosome-associated. The significance of this finding remains to be uncovered.

Beilstein Journal of Nanotechnology, 2020

We report on the synthesis of composite nanobeads with antibacterial properties. The particles co... more We report on the synthesis of composite nanobeads with antibacterial properties. The particles consist of polystyrene cores that are surrounded by sulfonic gel shells with embedded silver nanoparticles. The nanocomposite beads are prepared by sulfonation of polystyrene particles followed by accumulation of silver ions in the shell layer and subsequent reduction with sodium borohydride. The resulting material has been characterized by electron microscopy, vibrational and X-ray photoelectron spectroscopy and several other experimental techniques. It was shown that sodium borohydride reduces silver ions embedded in the gel layer producing silver nanoparticles but also transforms a fraction of sulfonic groups in the polymer to moieties with sulfur in a lower oxidation state, likely thiols. It is hypothesized that the generated thiol groups are anchoring the nanoparticles in the gel shell of the nanobeads stabilizing the whole structure. The silver-decorated nanobeads appear to be a prom...

Proceedings of the National Academy of Sciences, 1995

Transcription of downstream genes in the early operons of phage lambda requires a promoter-proxim... more Transcription of downstream genes in the early operons of phage lambda requires a promoter-proximal element known as nut. This site acts in cis in the form of RNA to assemble a transcription antitermination complex which is composed of lambda N protein and at least four host factors. The nut-site RNA contains a small stem-loop structure called boxB. Here, we show that boxB RNA binds to N protein with high affinity and specificity. While N binding is confined to the 5' subdomain of the stem-loop, specific N recognition relies on both an intact stem-loop structure and two critical nucleotides in the pentamer loop. Substitutions of these nucleotides affect both N binding and antitermination. Remarkably, substitutions of other loop nucleotides also diminish antitermination in vivo, yet they have no detectable effect on N binding in vitro. These 3' loop mutants fail to support antitermination in a minimal system with RNA polymerase (RNAP), N, and the host factor NusA. Furthermore...

Future microbiology, 2018

Pseudomonas aeruginosa is one of the most clinically important opportunistic pathogen in humans. ... more Pseudomonas aeruginosa is one of the most clinically important opportunistic pathogen in humans. The aim of the project was to study effects of HtpG on the selected virulence factors responsible for pathogenesis and biofilm formation of P. aeruginosa. By characterizing a htpG null mutant of P. aeruginosa, we have identified the role of HtpG in the production of selected factors. We showed that ΔhtpG mutant affects many physiological processes containing: decreased activity of the LasA protease, reduction of biofilm formation, decreased motility, and diminished amount of rhamnolipids and pyoverdine/pyocyanin. These defects were most evident when the ΔhtpG strain was cultured at 42°C. Our findings demonstrate the unexplored role of HtpG in the pathogenicity of P. aeruginosa, and indicate potential targets for antibacterial therapeutics. [Formula: see text].

Nanomedicine (London, England), May 1, 2018

To investigate the in vitro activity of silver NPs (AgNPs) against pathogenic microalgae of the P... more To investigate the in vitro activity of silver NPs (AgNPs) against pathogenic microalgae of the Prototheca genus. The antialgal potential of AgNPs against Prototheca species of both clinical and environmental origin was assessed from minimum inhibitory (algistatic) and algicidal concentrations. The in vitro cytotoxicity of AgNPs against bovine mammary epithelial cell line was evaluated by means of the standard MTT assay. AgNPs showed a strong killing activity toward Prototheca algae, as the minimal algicidal concentration (MAC) values matched perfectly the corresponding minimum inhibitory concentration (MIC) values for all species (MAC = MIC, 1-4 mg/l), except P. stagnora (MIC > 8 mg/l). The concentrations inhibitory to pathogenic Prototheca spp. (MIC, 1-4 mg/l) were below the concentrations at which any toxicity in epithelial cells could be observed (CC > 6 mg/l). The study emphasizes the potential of AgNPs as a new therapeutic tool for the management of Prototheca infections.

Bacteriophage X N gene product acts to modify host RNA polymerase allowing the formation of a ter... more Bacteriophage X N gene product acts to modify host RNA polymerase allowing the formation of a termination-resistant transcription apparatus. Previous studies have demonstrated that the nusE71 mutation that has altered the ribosomal protein S10 prevents N action in vivo. Using a coupled transcription-translation system, we demonstrate here that purified S10 protein as well as the 30S ribosomal subunit is sufficient to restore N activity in the nusE mutant extract, allowing antitermination of Rho-dependent and Rho-independent terminators. This provides direct biochemical evidence that the S10 protein itself is one of the cellular components necessary for the formation of an antitermination apparatus. The N gene product of bacteriophage X acts to suppress transcription termination in Escherichia coli (1-5). The action ofN depends on a recognition site (nut) encoded by the phage genome (6-9). It is thought that N acts to modify RNA polymerase at the nut site, allowing the formation of a...

Polish journal of microbiology / Polskie Towarzystwo Mikrobiologów = The Polish Society of Microbiologists, 2004

The content of fatty acids extracted from the membranes of E. coli MC 1061 harboring the wild-typ... more The content of fatty acids extracted from the membranes of E. coli MC 1061 harboring the wild-type dnaKdnaJ alleles and its delta dnaJ and delta dnaKdnaJ derivatives was compared. It was demonstrated that dodecanoic acid was missing in NPLs fraction extracted from both mutants grown at 42 degrees C. Phospholipids extracted from mutant strains were deprived of hexadecanoic acid methyl ester and octadecanol, the latter being correlated with the presence of octadecanoic acid. The amount of LPS extracted from delta dnaKdanJ mutant was significantly lower when compared with wild-type strain and delta dnaJ mutant.

Acta of bioengineering and biomechanics, 2016

The aim of the paper was to investigate the antifungal activity of zinc oxide nanoparticles (ZnON... more The aim of the paper was to investigate the antifungal activity of zinc oxide nanoparticles (ZnONPs) against Candida albicans. Some attempts have been made to find out the best way to introduce ZnONPs into polymethyl methacrylate (PMMA) resin material and to determine some parameters of a newly formed composite. Zinc oxide nanoparticles were manufactured and their basic physical parameters were determined (average particle size, density, specific surface area). Minimal inhibitory concentration (MIC) of ZnONPs was determined for the Candida albicans standard strain. The average size of ZnO conglomerates in the monomer solution of PMMA resin was measured using a dynamic light scattering instrument. PMMA resin samples with incorporated ZnONPs were produced. The morphology of nanopowder and the newly formed composite was examined under a scanning electron microscope (SEM). In addition, the roughness parameter of PMMA resin material was investigated before and after ZnONPs modification. ...

Acta Microbiologica Polonica, Feb 1, 2003

In the environment horizontal DNA transfer between various bacterial species and genera takes pla... more In the environment horizontal DNA transfer between various bacterial species and genera takes place by transformation, transduction, but mainly by conjugation. Conjugation is responsible for the spread of genes coding for antibiotic resistance and xenobiotic degradation. Transfer events are reported in animal, rhizosphere and phylloplane ecosystems and in non polluted and polluted water and soil. Genetic exchange between Bacteria and Archaea is also observed. Evaluation of the extent of interspecies gene transfer is crucial in view of the deliberate release of a variety of unmodified and genetically modified microorganisms into the natural environments.

Acta Microbiologica Polonica, Feb 1, 2002

Escherichia coli null dnaJ and dnaKdnaJ mutants, when introduced to Hfr donor, impair its ability... more Escherichia coli null dnaJ and dnaKdnaJ mutants, when introduced to Hfr donor, impair its ability to DNA transfer during conjugation. The additive effect of both mutations was shown. Lack of DnaK and DnaJ chaperones also decrease the extent of proteolysis in mutant strains. This effect is seen only at 42 degrees C. The influence of double dnaKdnaJ deletion but not single dnaJ deletion on novobiocin susceptibility was also demonstrated.

Folia Microbiol Prague, 2002

The effect of mutations in dnaK and dnaJ genes on the expression of two operons that are part of ... more The effect of mutations in dnaK and dnaJ genes on the expression of two operons that are part of cysteine regulon was determined using Escherichia coli strains harboring cysPTWA::lacZ and cysJIH::lacZ fusions. Null dnaJ and dnaKdnaJ mutants were impaired in [3-galactosidase expression from both fusions. Efficient complementation of this defect by wild-type alleles present on a low-copy number plasmid was achieved. The presence of the pMH224 plasmid coding for CysB* protein defective in DNA binding lowered [3-galactosidase expression from cysPTWA::lacZ fusion strain harboring wild-type dnaKdnaJ alleles but did not diminish enzyme expression in AdnaJ and AdnaKdnaJ strains.

Cell stress & chaperones, 2015

The bacterial chaperone high-temperature protein G (HtpG), a member of the Hsp90 protein family, ... more The bacterial chaperone high-temperature protein G (HtpG), a member of the Hsp90 protein family, is involved in the protection of cells against a variety of environmental stresses. The ability of HtpG to form complexes with other bacterial proteins, especially those involved in fundamental functions, is indicative of its cellular role. An interaction between HtpG and DnaA, the main initiator of DNA replication, was studied both in vivo, using a bacterial two-hybrid system, and in vitro with a modified pull-down assay and by chemical cross-linking. In vivo, this interaction was demonstrated only when htpG was expressed from a high copy number plasmid. Both in vitro assays confirmed HtpG-DnaA interactions.

Polish journal of microbiology / Polskie Towarzystwo Mikrobiologów = The Polish Society of Microbiologists, 2015

DnaJ chaperone, a member of the so called DnaK-DnaJ-GrpE chaperone machine plays an important rol... more DnaJ chaperone, a member of the so called DnaK-DnaJ-GrpE chaperone machine plays an important role in cell physiology. The ability of Escherichia coli ΔdnaJ mutant to form biofilm was studied. It was shown that this mutant is impaired in biofilm development when exposed to 42 degrees C for 2 h. The impairment in biofilm development was observed when the heat shock was applied either at the onset of biofilm formation or 2 h later. The biofilm formed was thinner and its structure was changed as compared to wild-type strain. This defect could be complemented by the introduction of a wild-type gene on a low-copy plasmid.

Journal of Applied Genetics, 2015

Nearly all bacterial species, including pathogens, have the ability to form biofilms. Biofilms ar... more Nearly all bacterial species, including pathogens, have the ability to form biofilms. Biofilms are defined as structured ecosystems in which microbes are attached to surfaces and embedded in a matrix composed of polysaccharides, eDNA, and proteins, and their development is a multistep process. Bacterial biofilms constitute a large medical problem due to their extremely high resistance to various types of therapeutics, including conventional antibiotics. Several environmental and genetic signals control every step of biofilm development and dispersal. From among the latter, quorum sensing, cyclic diguanosine-5'-monophosphate, and small RNAs are considered as the main regulators. The present review describes the control role of these three regulators in the life cycles of biofilms built by Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella enterica serovar Typhimurium, and Vibrio cholerae. The interconnections between their activities are shown. Compounds and strategies which target the activity of these regulators, mainly quorum sensing inhibitors, and their potential role in therapy are also assessed.

Methods in Enzymology, 1996

... Asis Das, Mahadeb Pal, Jaime Garcia Mena, William Whalen, Krystyna Wolska, Robin Crossley, Wi... more ... Asis Das, Mahadeb Pal, Jaime Garcia Mena, William Whalen, Krystyna Wolska, Robin Crossley, William Rees, Peter H. von Hippel, Nina Costantino, Donald Court, Marie Mazzulla, Amanda S. Altieri, R.Andrew Byrd, Samit Chattopadhyay, Joseph DeVito and Balaram Ghosh. ...

Acta microbiologica Polonica

RNA-dependent ATPase activity of Rho + and two mutant proteins Rho15 and Rho301 was studied. It w... more RNA-dependent ATPase activity of Rho + and two mutant proteins Rho15 and Rho301 was studied. It was shown that monomeric Rho forms oligomers in the presence of ATP. This ATP-induced structural change of Rho allows protection of the protein from heat inactivation. Poly(C), which highly activates Rho ATPase, was found to potentiate heat inactivation of Rho301, but no Rho + and Rho15, only under optimal conditions of ATP hydrolysis. It was also shown that Rho301 is defective in interaction with RNA. The molecular model postulating that Rho-catalysed ATP hydrolysis with free RNA involves the cyclic process of protein dissociation and reassembly is postulated.

Proceedings of the National Academy of Sciences, 1985

Bacteriophage X N gene product acts to modify host RNA polymerase allowing the formation of a ter... more Bacteriophage X N gene product acts to modify host RNA polymerase allowing the formation of a termination-resistant transcription apparatus. Previous studies have demonstrated that the nusE71 mutation that has altered the ribosomal protein S10 prevents N action in vivo. Using a coupled transcription-translation system, we demonstrate here that purified S10 protein as well as the 30S ribosomal subunit is sufficient to restore N activity in the nusE mutant extract, allowing antitermination of Rho-dependent and Rho-independent terminators. This provides direct biochemical evidence that the S10 protein itself is one of the cellular components necessary for the formation of an antitermination apparatus.

Acta microbiologica Polonica

Temperature sensitive dnaA recipient crossed at the restrictive temperature with HfrH, free from ... more Temperature sensitive dnaA recipient crossed at the restrictive temperature with HfrH, free from contaminating F+ cells, forms recombinants almost as proficiently as at the permissive temperature. The merozygotes are able to synthesize DNA at 42 degrees C, although the recipient and donor cells do not incorporate 3H-thymine. A substantial fraction of Lac+ recombinants, irrespective of the mating temperature, is temperature resistant (42 C-R); 15% from among those mated at 35 C and 30% from those mated at 42 C. The presence of dnaA mutation in these Lac+ 42 C-R recombinants was ascertained by co-transduction with ilv. Cell division at 42 C is inhibited in the Lac 42 C-R recombinants by acridine orange. The presence of F factor DNA in these recombinants was demonstrated directly by DNA: DNA hybridization. Suppression of dnaA mutation in Lac+ 42 degrees C-R recombinants and their sensitivity to acridine orange at 42 degrees C suggests that at least part of the F factor is integrated in...

Cell, 1984

Employing specifically engineered plasmids in which the expression of E. coli galK cistron is reg... more Employing specifically engineered plasmids in which the expression of E. coli galK cistron is regulated by transcription termination, we have analyzed the antitermination function of phage X N gene product in S30 extracts. Antitermination by N, dependent on its site of action, nut& is defective in the extracts prepared from nusA, n&3, and nusE mutants. By complementation analysis, we demonstrate that none of the these nus mutations affects the synthesis of N or the other nus gene products to cause a defect in antiterminatlon. Rather, these mutations have inactivated a set of specific host components, the Nus factors, which are essential for N activity. Curiously, an appreciable portion of N and Nus complementation activities of an S30 extract is ribosome-associated. The significance of this finding remains to be uncovered.