Erzsebet Fejes - Academia.edu (original) (raw)

Papers by Erzsebet Fejes

Plant Cell, 2002

The phytochrome family of plant photoreceptors has a central role in the adaptation of plant deve... more The phytochrome family of plant photoreceptors has a central role in the adaptation of plant development to changes in ambient light conditions. The individual phytochrome species regulate different or partly overlapping physiological responses. We generated transgenic Arabidopsis plants expressing phytochrome A to E:green fluorescent protein (GFP) fusion proteins to assess the biological role of intracellular compartmentation of these photoreceptors in

The Plant Journal, 1997

Higher plants, similarly to other eukaryotic organisms, contain a superfamily of genes coding for... more Higher plants, similarly to other eukaryotic organisms, contain a superfamily of genes coding for Ras-related, Summary small GTP-binding proteins . According to the postulated functions of these plant proteins, this Ran, a small soluble GTP-binding protein, has been shown superfamily is subdivided into three subfamilies that repto be essential for the nuclear translocation of proteins resent (i) the membrane-bound Rab/Ypt-type-proteins and it is also thought to be involved in regulating cell involved in regulating vesicular trafficking (Terryn et al., cycle progression in mammalian and yeast cells. Genes 1993), (ii) the membrane-bound Rho/Rac-type proteins encoding Ran-like proteins have been isolated from differthought to be important for cytoskeleton organization ent higher plant species. Overexpression of plant Ran (Yang and Watson, 1993) and (iii) the soluble Ran (Ras-cDNAs, similarly to their mammalian/yeast homologues, related nuclear protein) that is most probably necessary suppresses the phenotype of the pim46-1 cell cycle mutant for protein import into the nucleus and for the onset of in yeast cells. The mammalian/yeast Ran proteins have mitosis (Ach and Gruissem, 1994;. The been shown to interact with a battery of Ran-binding mammalian Ran cDNA, originally identified as TC4 (Drivas proteins, including the guanidine nucleotide exchange et al., 1990) codes for a 25 kDa nuclear protein and has factor RCC1, the GTPase-activating Ran-GAP, nucleoporins been shown to bind to the chromatin-associated protein and other Ran-binding proteins (RanBPs) specific for Ran- RCC1 (Bischoff and Ponstingl, 1991a). A temperature-sens-GTP. Here, the characterization of the first Ran-binding itive tsBN2 hamster cell line containing a defective RCC1 proteins from higher plants is reported. The yeast twogene (the regulator of chromosome condensation) has hybrid system was used to isolate cDNA clones encoding been shown to form micronuclei and is unable to complete proteins of approximately 28 kDa (At-RanBP1a, Atmitosis properly Nishitani et al., RanBP1b) that interact with the GTP-bound forms of the 1991). Several Schizzosaccharomyces pombe, Saccharo-Ran1, Ran2 and Ran3 proteins of Arabidopsis thaliana. The myces cerevisae and Drosophila mutants defective in the deduced amino acid sequences of the At-RanBP1s display RCC1 homologue pim1, PRP20/SRM1/MTR1 and BJ1 genes, high similarity (60%) to mammalian/yeast RanBP1 proteins respectively, have been isolated. However, these mutants and contain the characteristic Ran-binding domains.

THE PLANT CELL ONLINE, 2004

Light, in a quality-and quantity-dependent fashion, induces nuclear import of the plant photorece... more Light, in a quality-and quantity-dependent fashion, induces nuclear import of the plant photoreceptors phytochrome, promotes interaction of phytochrome A (phyA) and phyB with transcription factors including phytochrome interacting factor 3 (PIF3), and is thought to trigger a transcriptional cascade to regulate the expression of ;2500 genes in Arabidopsis thaliana. Here, we show that controlled degradation of the transcription factor PIF3 is a major regulatory step in light signaling. We demonstrate that accumulation of PIF3 in the nucleus in dark requires constitutive photomorphogenesis 1 (COP1), a negative regulator of photomorphogenesis, and show that red (R) and far-red light (FR) induce rapid degradation of the PIF3 protein. This process is controlled by the concerted action of the R/FR absorbing phyA, phyB, and phyD photoreceptors, and it is not affected by COP1. Rapid light-induced degradation of PIF3 indicates that interaction of PIF3 with these phytochrome species is transient. In addition, we provide evidence that the poc1 mutant, a postulated PIF3 overexpressor that displays hypersensitivity to R but not to FR, lacks detectable amounts of the PIF3 protein. Thus, we propose that PIF3 acts transiently, and its major function is to mediate phytochrome-induced signaling during the developmental switch from skotomorphogenesis to photomorphogenesis and/or dark to light transitions.

Proceedings of the National Academy of Sciences, 1985

Genetic recombination between chloroplasts of two flowering plant species, Nicotiana tabacum and ... more Genetic recombination between chloroplasts of two flowering plant species, Nicotiana tabacum and Nicotiana plumbaginifolia, after somatic cell fusion is described. The parental lines differed in three cytoplasmic genetic markers. The N. tabacum mutant SR1-A15 was streptomycin-resistant, defective in chloroplast greening, and lincomycin-sensitive. The N. plumbaginifolia mutant LR400 was streptomycin-sensitive, normal green, and lincomycin-resistant. Streptomycin-resistant clones in cell culture are identified by their ability to form a green callus on a selective medium. Streptomycin resistance in the SR1-A15 mutant could not be expressed due to defective chloroplasts. Protoplasts of the two species were fused, and calli grown from the fused population were screened for the expression of streptomycin resistance from the SR1-A15 line as the result of interspecific chloroplast recombination. A somatic hybrid, pt14, expressed a new combination of the cytoplasmic genetic markers. In the pt14 chloroplast genome three N. tabacum and four N. plumbaginifolia parent specific restriction sites have been identified, indicating that the pt14 chloroplast genome contains at least six recombination sites.

Plant and Cell Physiology, 2005

Light, in a quality-and quantity-dependent fashion, induces nuclear import of the plant photorece... more Light, in a quality-and quantity-dependent fashion, induces nuclear import of the plant photoreceptors phytochromes and promotes interaction of these receptors with transcription factors including PHYTOCHROME INTER-ACTING FACTOR 3 (PIF3). PIF3 was shown to form in vitro a ternary complex with the G-box element of the promoters of LATE ELONGATED HYPOCOTYL (LHY) and CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) and the Pfr conformer of phytochromes. CCA1 and LHY together with TIMING OF CAB EXPRESSION 1 (TOC1) constitute a transcriptional feed-back loop that is essential for a functional circadian clock in Arabidopsis. These findings led to the hypothesis that the PIF3-containing ternary complex regulates transcription of light-responsive genes and is involved in phototransduction to the central circadian clockwork. Here we report that (i) overexpression or lack of biologically functional PIF3 does not affect period length of rhythmic gene expression or red-light-induced resetting of the circadian clock and (ii) the transcription of PIF3 displays a low-amplitude circadian rhythm. We demonstrated previously that irradiation of etiolated seedlings induces rapid, phytochrome-controlled degradation of PIF3. Here we show that nuclear-localized PIF3 accumulates to relatively high levels by the end of the light phase in seedlings grown under diurnal conditions. Taken together, we show that (i) PIF3 does not play a significant role in controlling light input to and function of the circadian clockwork and (ii) a yet unknown mechanism limits phytochrome-induced degradation of PIF3 at the end of the day under diurnal conditions.

Journal of Experimental Botany, 2007

The A-type response regulator ARR4 is an element in the two-component signalling network of Arabi... more The A-type response regulator ARR4 is an element in the two-component signalling network of Arabidopsis. ARR4 interacts with the N-terminus of the red/far-red light photoreceptor phytochrome B (phyB) and functions as a modulator of photomorphogenesis. In concert with other A-type response regulators, ARR4 also participates in the modulation of the cytokinin response pathway. Here evidence is presented that ARR4 directly modulates the activity state of phyB in planta, not only under inductive but also under extended irradiation with red light. Mutation of the phosphorylatable aspartate to asparagine within the receiver domain creates a version of ARR4 that negatively affects photomorphogenesis. Additional evidence suggests that ARR4 activity is regulated by a phosphorelay mechanism that depends on the AHK family of cytokinin receptors. Accordingly, the ability of ARR4 to function on phyB is modified by exogenous application of cytokinin. These results implicate a cross-talk between cytokinin and light signalling mediated by ARR4. This cross-talk enables the plant to adjust light reponsiveness to endogenous requirements in growth and development.

Current Genetics, 1988

The complete sequence of a mitochondrial DNA insertional event containing the 3' portion ... more The complete sequence of a mitochondrial DNA insertional event containing the 3' portion of the chloroplast 23S-4.5S rRNA gene, the entire 5S rRNA gene and intervening sequence and all but the 3' 6 nucleotides of the arginine tRNA gene is reported. Also reported are both chloroplast/mitochondrial DNA junction sequences, 551 nucleotides of flanking mitochondrial sequences and the genomic location of this insert in Zea mays mitochondria. Utilizing the distinctive transcriptional pattern seen for mitochondrial RNA derived from root tissue relative to shoot tissue, we also reported a general experimental test for whether chloroplast sequences transposed to the mitochondrion are transcribed. Although results for the insert reported suggest it is transcriptionally inactive, the technique should be generally applicable to any transposed sequence.

The Plant Journal, 2002

In animals and yeast, the small GTP-binding protein Ran has multiple functions ± it is involved i... more In animals and yeast, the small GTP-binding protein Ran has multiple functions ± it is involved in mediating (i) the directional passage of proteins and RNA through the nuclear pores in interphase cells; and (ii) the formation of spindle asters, the polymerization of microtubules, and the re-assembly of the nuclear envelope in mitotic cells. Nucleotide binding of Ran is modulated by a series of accessory proteins. For instance, the hydrolysis of RanGTP requires stimulation by the RanGTPase protein RanGAP.

Plant Cell, 2002

The phytochrome family of plant photoreceptors has a central role in the adaptation of plant deve... more The phytochrome family of plant photoreceptors has a central role in the adaptation of plant development to changes in ambient light conditions. The individual phytochrome species regulate different or partly overlapping physiological responses. We generated transgenic Arabidopsis plants expressing phytochrome A to E:green fluorescent protein (GFP) fusion proteins to assess the biological role of intracellular compartmentation of these photoreceptors in

The Plant Journal, 1997

Higher plants, similarly to other eukaryotic organisms, contain a superfamily of genes coding for... more Higher plants, similarly to other eukaryotic organisms, contain a superfamily of genes coding for Ras-related, Summary small GTP-binding proteins . According to the postulated functions of these plant proteins, this Ran, a small soluble GTP-binding protein, has been shown superfamily is subdivided into three subfamilies that repto be essential for the nuclear translocation of proteins resent (i) the membrane-bound Rab/Ypt-type-proteins and it is also thought to be involved in regulating cell involved in regulating vesicular trafficking (Terryn et al., cycle progression in mammalian and yeast cells. Genes 1993), (ii) the membrane-bound Rho/Rac-type proteins encoding Ran-like proteins have been isolated from differthought to be important for cytoskeleton organization ent higher plant species. Overexpression of plant Ran (Yang and Watson, 1993) and (iii) the soluble Ran (Ras-cDNAs, similarly to their mammalian/yeast homologues, related nuclear protein) that is most probably necessary suppresses the phenotype of the pim46-1 cell cycle mutant for protein import into the nucleus and for the onset of in yeast cells. The mammalian/yeast Ran proteins have mitosis (Ach and Gruissem, 1994;. The been shown to interact with a battery of Ran-binding mammalian Ran cDNA, originally identified as TC4 (Drivas proteins, including the guanidine nucleotide exchange et al., 1990) codes for a 25 kDa nuclear protein and has factor RCC1, the GTPase-activating Ran-GAP, nucleoporins been shown to bind to the chromatin-associated protein and other Ran-binding proteins (RanBPs) specific for Ran- RCC1 (Bischoff and Ponstingl, 1991a). A temperature-sens-GTP. Here, the characterization of the first Ran-binding itive tsBN2 hamster cell line containing a defective RCC1 proteins from higher plants is reported. The yeast twogene (the regulator of chromosome condensation) has hybrid system was used to isolate cDNA clones encoding been shown to form micronuclei and is unable to complete proteins of approximately 28 kDa (At-RanBP1a, Atmitosis properly Nishitani et al., RanBP1b) that interact with the GTP-bound forms of the 1991). Several Schizzosaccharomyces pombe, Saccharo-Ran1, Ran2 and Ran3 proteins of Arabidopsis thaliana. The myces cerevisae and Drosophila mutants defective in the deduced amino acid sequences of the At-RanBP1s display RCC1 homologue pim1, PRP20/SRM1/MTR1 and BJ1 genes, high similarity (60%) to mammalian/yeast RanBP1 proteins respectively, have been isolated. However, these mutants and contain the characteristic Ran-binding domains.

THE PLANT CELL ONLINE, 2004

Light, in a quality-and quantity-dependent fashion, induces nuclear import of the plant photorece... more Light, in a quality-and quantity-dependent fashion, induces nuclear import of the plant photoreceptors phytochrome, promotes interaction of phytochrome A (phyA) and phyB with transcription factors including phytochrome interacting factor 3 (PIF3), and is thought to trigger a transcriptional cascade to regulate the expression of ;2500 genes in Arabidopsis thaliana. Here, we show that controlled degradation of the transcription factor PIF3 is a major regulatory step in light signaling. We demonstrate that accumulation of PIF3 in the nucleus in dark requires constitutive photomorphogenesis 1 (COP1), a negative regulator of photomorphogenesis, and show that red (R) and far-red light (FR) induce rapid degradation of the PIF3 protein. This process is controlled by the concerted action of the R/FR absorbing phyA, phyB, and phyD photoreceptors, and it is not affected by COP1. Rapid light-induced degradation of PIF3 indicates that interaction of PIF3 with these phytochrome species is transient. In addition, we provide evidence that the poc1 mutant, a postulated PIF3 overexpressor that displays hypersensitivity to R but not to FR, lacks detectable amounts of the PIF3 protein. Thus, we propose that PIF3 acts transiently, and its major function is to mediate phytochrome-induced signaling during the developmental switch from skotomorphogenesis to photomorphogenesis and/or dark to light transitions.

Proceedings of the National Academy of Sciences, 1985

Genetic recombination between chloroplasts of two flowering plant species, Nicotiana tabacum and ... more Genetic recombination between chloroplasts of two flowering plant species, Nicotiana tabacum and Nicotiana plumbaginifolia, after somatic cell fusion is described. The parental lines differed in three cytoplasmic genetic markers. The N. tabacum mutant SR1-A15 was streptomycin-resistant, defective in chloroplast greening, and lincomycin-sensitive. The N. plumbaginifolia mutant LR400 was streptomycin-sensitive, normal green, and lincomycin-resistant. Streptomycin-resistant clones in cell culture are identified by their ability to form a green callus on a selective medium. Streptomycin resistance in the SR1-A15 mutant could not be expressed due to defective chloroplasts. Protoplasts of the two species were fused, and calli grown from the fused population were screened for the expression of streptomycin resistance from the SR1-A15 line as the result of interspecific chloroplast recombination. A somatic hybrid, pt14, expressed a new combination of the cytoplasmic genetic markers. In the pt14 chloroplast genome three N. tabacum and four N. plumbaginifolia parent specific restriction sites have been identified, indicating that the pt14 chloroplast genome contains at least six recombination sites.

Plant and Cell Physiology, 2005

Light, in a quality-and quantity-dependent fashion, induces nuclear import of the plant photorece... more Light, in a quality-and quantity-dependent fashion, induces nuclear import of the plant photoreceptors phytochromes and promotes interaction of these receptors with transcription factors including PHYTOCHROME INTER-ACTING FACTOR 3 (PIF3). PIF3 was shown to form in vitro a ternary complex with the G-box element of the promoters of LATE ELONGATED HYPOCOTYL (LHY) and CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) and the Pfr conformer of phytochromes. CCA1 and LHY together with TIMING OF CAB EXPRESSION 1 (TOC1) constitute a transcriptional feed-back loop that is essential for a functional circadian clock in Arabidopsis. These findings led to the hypothesis that the PIF3-containing ternary complex regulates transcription of light-responsive genes and is involved in phototransduction to the central circadian clockwork. Here we report that (i) overexpression or lack of biologically functional PIF3 does not affect period length of rhythmic gene expression or red-light-induced resetting of the circadian clock and (ii) the transcription of PIF3 displays a low-amplitude circadian rhythm. We demonstrated previously that irradiation of etiolated seedlings induces rapid, phytochrome-controlled degradation of PIF3. Here we show that nuclear-localized PIF3 accumulates to relatively high levels by the end of the light phase in seedlings grown under diurnal conditions. Taken together, we show that (i) PIF3 does not play a significant role in controlling light input to and function of the circadian clockwork and (ii) a yet unknown mechanism limits phytochrome-induced degradation of PIF3 at the end of the day under diurnal conditions.

Journal of Experimental Botany, 2007

The A-type response regulator ARR4 is an element in the two-component signalling network of Arabi... more The A-type response regulator ARR4 is an element in the two-component signalling network of Arabidopsis. ARR4 interacts with the N-terminus of the red/far-red light photoreceptor phytochrome B (phyB) and functions as a modulator of photomorphogenesis. In concert with other A-type response regulators, ARR4 also participates in the modulation of the cytokinin response pathway. Here evidence is presented that ARR4 directly modulates the activity state of phyB in planta, not only under inductive but also under extended irradiation with red light. Mutation of the phosphorylatable aspartate to asparagine within the receiver domain creates a version of ARR4 that negatively affects photomorphogenesis. Additional evidence suggests that ARR4 activity is regulated by a phosphorelay mechanism that depends on the AHK family of cytokinin receptors. Accordingly, the ability of ARR4 to function on phyB is modified by exogenous application of cytokinin. These results implicate a cross-talk between cytokinin and light signalling mediated by ARR4. This cross-talk enables the plant to adjust light reponsiveness to endogenous requirements in growth and development.

Current Genetics, 1988

The complete sequence of a mitochondrial DNA insertional event containing the 3' portion ... more The complete sequence of a mitochondrial DNA insertional event containing the 3' portion of the chloroplast 23S-4.5S rRNA gene, the entire 5S rRNA gene and intervening sequence and all but the 3' 6 nucleotides of the arginine tRNA gene is reported. Also reported are both chloroplast/mitochondrial DNA junction sequences, 551 nucleotides of flanking mitochondrial sequences and the genomic location of this insert in Zea mays mitochondria. Utilizing the distinctive transcriptional pattern seen for mitochondrial RNA derived from root tissue relative to shoot tissue, we also reported a general experimental test for whether chloroplast sequences transposed to the mitochondrion are transcribed. Although results for the insert reported suggest it is transcriptionally inactive, the technique should be generally applicable to any transposed sequence.

The Plant Journal, 2002

In animals and yeast, the small GTP-binding protein Ran has multiple functions ± it is involved i... more In animals and yeast, the small GTP-binding protein Ran has multiple functions ± it is involved in mediating (i) the directional passage of proteins and RNA through the nuclear pores in interphase cells; and (ii) the formation of spindle asters, the polymerization of microtubules, and the re-assembly of the nuclear envelope in mitotic cells. Nucleotide binding of Ran is modulated by a series of accessory proteins. For instance, the hydrolysis of RanGTP requires stimulation by the RanGTPase protein RanGAP.