The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
Carin K Vanderpool - One of the best experts on this subject based on the ideXlab platform.
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the small protein sgrt controls transport activity of the Glucose specific phosphotransferase system
Journal of Bacteriology, 2017Co-Authors: Chelsea R Lloyd, Seongjin Park, Jingyi Fei, Carin K VanderpoolAbstract:The bacterial small RNA (sRNA) SgrS has been a fruitful model for discovery of novel RNA-based regulatory mechanisms and new facets of bacterial physiology and metabolism. SgrS is one of only a few characterized dual-function sRNAs. SgrS can control gene expression posttranscriptionally via sRNA-mRNA base-pairing interactions. Its second function is coding for the small protein SgrT. Previous work demonstrated that both functions contribute to relief of growth inhibition caused by Glucose-Phosphate stress, a condition characterized by disrupted glycolytic flux and accumulation of sugar Phosphates. The base-pairing activity of SgrS has been the subject of numerous studies, but the activity of SgrT is less well characterized. Here, we provide evidence that SgrT acts to specifically inhibit the transport activity of the major Glucose permease PtsG. Superresolution microscopy demonstrated that SgrT localizes to the cell membrane in a PtsG-dependent manner. Mutational analysis determined that residues in the N-terminal domain of PtsG are important for conferring sensitivity to SgrT-mediated inhibition of transport activity. Growth assays support a model in which SgrT-mediated inhibition of PtsG transport activity reduces accumulation of nonmetabolizable sugar Phosphates and promotes utilization of alternative carbon sources by modulating carbon catabolite repression. The results of this study expand our understanding of a basic and well-studied biological problem, namely, how cells coordinate carbohydrate transport and metabolism. Further, this work highlights the complex activities that can be carried out by sRNAs and small proteins in bacteria.IMPORTANCE Sequencing, annotation and investigation of hundreds of bacterial genomes have identified vast numbers of small RNAs and small proteins, the majority of which have no known function. In this study, we explore the function of a small protein that acts in tandem with a well-characterized small RNA during metabolic stress to help bacterial cells maintain balanced metabolism and continue growing. Our results indicate that this protein acts on the Glucose transport system, inhibiting its activity under stress conditions in order to allow cells to utilize alternative carbon sources. This work sheds new light on a key biological problem: how cells coordinate carbohydrate transport and metabolism. The study also expands our understanding of the functional capacities of small proteins.
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a dual function for a bacterial small rna sgrs performs base pairing dependent regulation and encodes a functional polypeptide
Proceedings of the National Academy of Sciences of the United States of America, 2007Co-Authors: Caryn Wadler, Carin K VanderpoolAbstract:SgrS is a 227-nt small RNA that is expressed in Escherichia coli during Glucose-Phosphate stress, a condition associated with intracellular accumulation of Glucose-6-Phosphate caused by disruption of glycolytic flux. Under stress conditions, SgrS negatively regulates translation and stability of the ptsG mRNA, encoding the major Glucose transporter, by means of a base pairing-dependent mechanism requiring the RNA chaperone Hfq. SgrS activity mitigates the effects of Glucose-Phosphate stress, and the present study has elucidated a function of SgrS that is proposed to contribute to the stress response. The 5′ end of SgrS, upstream of the nucleotides involved in base pairing with the ptsG mRNA, contains a 43-aa ORF, sgrT, that is conserved in most species that contain SgrS-like small RNAs. The sgrT gene is translated in E. coli under conditions of Glucose-Phosphate stress. Analysis of alleles that separate the base pairing function of SgrS from the sgrT coding sequence revealed that either of these functions alone are sufficient for previously characterized SgrS phenotypes. SgrS-dependent down-regulation of ptsG mRNA stability does not require SgrT and SgrT by itself has no effect on ptsG mRNA stability. Cells expressing sgrT alone had a defect in Glucose uptake even though they had nearly wild-type levels of PtsG (IICBGlc). Together, these data suggest that SgrS represents a previously unrecognized paradigm for small RNA (sRNA) regulators as a bifunctional RNA that encodes physiologically redundant but mechanistically distinct functions contributing to the same stress response.
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involvement of a novel transcriptional activator and small rna in post transcriptional regulation of the Glucose phosphoenolpyruvate phosphotransferase system
Molecular Microbiology, 2004Co-Authors: Carin K Vanderpool, Susan GottesmanAbstract:: RyaA is a small non-coding RNA in Escherichia coli that was identified by its ability to bind tightly to the RNA chaperone Hfq. This study reports the role of RyaA in mediating the cellular response to Glucose-specific phosphoenolypyruvate phosphotransferase system (PTS)-dependent phosphosugar stress. Aiba and co-workers have shown that a block in the metabolism of Glucose 6-Phosphate causes transient growth inhibition and post-transcriptional regulation of ptsG, encoding the Glucose-specific PTS transporter. We found that RyaA synthesis was induced by a non-metabolizable Glucose Phosphate analogue and was necessary for relief of the toxicity of Glucose Phosphate stress. Expression of RyaA was sufficient to cause a rapid loss of ptsG mRNA, probably reflecting degradation of the message mediated by RyaA:ptsG pairing. The ryaA gene was renamed sgrS, for sugar transport-related sRNA. Expression of sgrS is regulated by a novel transcriptional activator, SgrR (formerly YabN), which has a putative DNA-binding domain and a solute-binding domain similar to those found in certain transport proteins. Our results suggest that under conditions of Glucose Phosphate accumulation, SgrR activates SgrS synthesis, causing degradation of ptsG mRNA. Decreased ptsG mRNA results in decreased production of Glucose transport machinery, thus limiting further accumulation of Glucose Phosphate.
Caryn Wadler - One of the best experts on this subject based on the ideXlab platform.
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a dual function for a bacterial small rna sgrs performs base pairing dependent regulation and encodes a functional polypeptide
Proceedings of the National Academy of Sciences of the United States of America, 2007Co-Authors: Caryn Wadler, Carin K VanderpoolAbstract:SgrS is a 227-nt small RNA that is expressed in Escherichia coli during Glucose-Phosphate stress, a condition associated with intracellular accumulation of Glucose-6-Phosphate caused by disruption of glycolytic flux. Under stress conditions, SgrS negatively regulates translation and stability of the ptsG mRNA, encoding the major Glucose transporter, by means of a base pairing-dependent mechanism requiring the RNA chaperone Hfq. SgrS activity mitigates the effects of Glucose-Phosphate stress, and the present study has elucidated a function of SgrS that is proposed to contribute to the stress response. The 5′ end of SgrS, upstream of the nucleotides involved in base pairing with the ptsG mRNA, contains a 43-aa ORF, sgrT, that is conserved in most species that contain SgrS-like small RNAs. The sgrT gene is translated in E. coli under conditions of Glucose-Phosphate stress. Analysis of alleles that separate the base pairing function of SgrS from the sgrT coding sequence revealed that either of these functions alone are sufficient for previously characterized SgrS phenotypes. SgrS-dependent down-regulation of ptsG mRNA stability does not require SgrT and SgrT by itself has no effect on ptsG mRNA stability. Cells expressing sgrT alone had a defect in Glucose uptake even though they had nearly wild-type levels of PtsG (IICBGlc). Together, these data suggest that SgrS represents a previously unrecognized paradigm for small RNA (sRNA) regulators as a bifunctional RNA that encodes physiologically redundant but mechanistically distinct functions contributing to the same stress response.
Chelsea R Lloyd - One of the best experts on this subject based on the ideXlab platform.
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the small protein sgrt controls transport activity of the Glucose specific phosphotransferase system
Journal of Bacteriology, 2017Co-Authors: Chelsea R Lloyd, Seongjin Park, Jingyi Fei, Carin K VanderpoolAbstract:The bacterial small RNA (sRNA) SgrS has been a fruitful model for discovery of novel RNA-based regulatory mechanisms and new facets of bacterial physiology and metabolism. SgrS is one of only a few characterized dual-function sRNAs. SgrS can control gene expression posttranscriptionally via sRNA-mRNA base-pairing interactions. Its second function is coding for the small protein SgrT. Previous work demonstrated that both functions contribute to relief of growth inhibition caused by Glucose-Phosphate stress, a condition characterized by disrupted glycolytic flux and accumulation of sugar Phosphates. The base-pairing activity of SgrS has been the subject of numerous studies, but the activity of SgrT is less well characterized. Here, we provide evidence that SgrT acts to specifically inhibit the transport activity of the major Glucose permease PtsG. Superresolution microscopy demonstrated that SgrT localizes to the cell membrane in a PtsG-dependent manner. Mutational analysis determined that residues in the N-terminal domain of PtsG are important for conferring sensitivity to SgrT-mediated inhibition of transport activity. Growth assays support a model in which SgrT-mediated inhibition of PtsG transport activity reduces accumulation of nonmetabolizable sugar Phosphates and promotes utilization of alternative carbon sources by modulating carbon catabolite repression. The results of this study expand our understanding of a basic and well-studied biological problem, namely, how cells coordinate carbohydrate transport and metabolism. Further, this work highlights the complex activities that can be carried out by sRNAs and small proteins in bacteria.IMPORTANCE Sequencing, annotation and investigation of hundreds of bacterial genomes have identified vast numbers of small RNAs and small proteins, the majority of which have no known function. In this study, we explore the function of a small protein that acts in tandem with a well-characterized small RNA during metabolic stress to help bacterial cells maintain balanced metabolism and continue growing. Our results indicate that this protein acts on the Glucose transport system, inhibiting its activity under stress conditions in order to allow cells to utilize alternative carbon sources. This work sheds new light on a key biological problem: how cells coordinate carbohydrate transport and metabolism. The study also expands our understanding of the functional capacities of small proteins.
Simon Kilvington - One of the best experts on this subject based on the ideXlab platform.
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Identification of Naegleria fowleri and other Naegleria spp. (free-living amoebae) using cellulose acetate membrane electrophoresis of Glucose Phosphate isomerase
FEMS Microbiology Letters, 1995Co-Authors: Simon KilvingtonAbstract:A simple isoenzyme cellulose acetate membrane electrophoresis method with respect to Glucose Phosphate isomerase (GPI) was developed for the differentiation of the human pathogenic free-living amoeba Naegleria fowleri from other Naegleria spp. A single GPI band was detected in all the species tested, the relative mobility of which could be used to identify N. fowleri. Of the other Naegleria spp., only N. italica and N. jadini shared a common GPI mobility. No intraspecies variation in GPI profile was detected, regardless of whether the strains were cultured in monoxenic or axenic media. The technique is proposed as a useful means of identifying N. fowleri soon after isolation from the environment.
Hans O Portner - One of the best experts on this subject based on the ideXlab platform.
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variation in genetic traits of the lugworm arenicola marina temperature related expression of mitochondrial allozymes
Marine Ecology Progress Series, 1997Co-Authors: Herman Hummel, R.h. Bogaards, Angela Sommer, Hans O PortnerAbstract:Genetic traits of the lugworm Arenicola marina were determined for four Atlantic populations from France to Norway and compared with a population from the sub-arctic White Sea in Russia. Seven loci were analysed using horizontal starch gel electrophoresis. A low heterozygosity (0.09-0.17) and a non-significant heterozygote deficiency were found in all populations. The genetic identity between lugworms of European Atlantic populations was high, whereas similarity of the Atlantic populations with the population from the White Sea was low. The gene flow between the Atlantic and the White Sea populations must be considered negligible, as deduced from the average high and significant gene differentiation FST. In particular, differences in allele frequencies of Glucose Phosphate isomerase (Gpi) and phosphoglucomutase (Pgm) showed that the White Sea population differed significantly from the others. A very strong correlation existed between the frequency of the alleles of isocitrate dehydrogenases 2-A and -B (Idh2-A and Idh2-B) and the average water temperature. It is concluded that temperature had a selective influence on isocitrate dehydrogenase 2, which, in contrast to isocitrate dehydrogenase 1, was identified as a mitochondrial enzyme. These findings support the hypothesis that mitochondria play a key role in temperature adaptation and the adjustment of critical temperatures.