Global analysis of mRNA decay intermediates in Bacillus subtilis wild-type and polynucleotide phosphorylase-deletion strains
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ABSTRACT:
ORGANISM(S): Bacillus subtilis
PROVIDER: GSE120050 | GEO | 2018/09/18
REPOSITORIES: GEO
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Project description:The Bacillus subtilis genome encodes four 3’ exoribonucleases: polynucleotide phosphorylase (PNPase), RNase R, RNase PH, and YhaM. Previous work showed that PNPase, encoded by the pnpA gene, is the major 3’ exonuclease involved in mRNA turnover; in a pnpA deletion strain, numerous mRNA decay intermediates accumulate. Whether B. subtilis mRNA decay occurs in the context of a degradosome complex is controversial. In this study, global mapping of mRNA decay intermediate 3’ ends within coding sequences was performed in strains that were either deleted for, or had an inactivating point mutation in, the pnpA gene. The pattern of 3’ end accumulation in these strains was highly similar, suggesting that mRNA decay was not occurring in the context of a degradosome, whose structure would be affected by the absence of PNPase. A comparison with mapped 3’ ends in a strain lacking CshA, the major RNA helicase, indicated that different mRNAs may require both PNPase and CshA for efficient decay. RNA-seq analysis of strains lacking RNase R suggested that this enzyme did not play a major role in mRNA turnover in the wild-type strain. Strains were constructed that contained only one of the four known 3’ exoribonucleases. When RNase R was the only 3’ exonuclease present, it was able to degrade a model mRNA efficiently, showing processive decay even through a strong stem-loop structure that inhibits PNPase processivity. Strains containing only RNase PH or only YhaM were also insensitive to this RNA secondary structure, suggesting the existence of another, as-yet unidentified, 3’ exoribonuclease.
2022-01-03 | GSE192670 | GEO
Project description:In many gram-negative and some gram-positive bacteria small regulatory RNAs (sRNAs) that bind the RNA chaperone Hfq have a pivotal role in modulating virulence, stress responses, metabolism, and biofilm formation. These sRNAs recognize transcripts through base-pairing, and sRNA-mRNA annealing consequently alters the translation and/or stability of transcripts leading to changes in gene expression. We have previously found that the highly conserved 3'-to-5' exoribonuclease polynucleotide phosphorylase (PNPase) has an indispensable role in paradoxically stabilizing Hfq-bound sRNAs and promoting their function in gene regulation in Escherichia coli. Here, we report that PNPase uniquely contributes to the degradation of specific mRNA cleavage products, the majority of which bind Hfq and are derived from targets of sRNAs. Specifically, we found that these mRNA-derived fragments accumulate in the absence of PNPase or its exoribonuclease activity and interact with PNPase. Additionally, we show that mutations in hfq or in the seed pairing region of a sRNA eliminated the requirement of PNPase for sRNA stability. Altogether, our results are consistent with a model that PNPase degrades mRNA-derived fragments that could otherwise deplete cells of Hfq-binding sRNAs through pairing mediated decay.
2019-07-08 | GSE125368 | GEO
Project description:In all bacterial species examined thusfar, small regulatory RNAs (sRNAs) contribute to intricate patterns of genetic regulation. Many of the actions of these nucleic acids are mediated by chaperones such as the Hfq protein, and genetic screens have identified the exoribonuclease polynucleotide phosphorylase (PNPase) as a stabilizer and facilitator of sRNAs in vivo. We observe that the protective and facilitating effects of PNPase in vivo require the RNA-binding KH and S1 domains and the catalytic site, suggesting a requirement for physical interation of the ribonuclease with either the sRNA itself or other RNAs acting upstream of the process. Although purified PNPase can readily degrade sRNAs in vitro, those same substrates, as well as numerous other sRNAs and transcripts, can be co-purified from cells by immunoprecipitation with neither degradation nor modification to the 3â end. Our results indicate that PNPase can bind RNA in two modes in vivo â either destructive or stabilizing, and that there is active flux of RNAs on PNPase so that the stable molecules do not accumulate. In the presence of Hfq, PNPase and sRNA form a ternary complex in which the enzyme plays a non-destructive, structural role, but the complex does not confer protection against the action of RNase E in vitro. Taken together, our results indicate that PNPase, Hfq and additional factors form a protective ribonucleoprotein assembly that stabilizes certain sRNAs and facilitates their activities. Using cells from the same original culture, immunoprecipitiations using the anti-FLAG M2 resin were performed in the presence or absence of tungstate. Total RNA and immunoprecipitated RNA were sequenced from two independent biological replicates. The number of normalized reads (RPKM) were compared between the total RNA (input) and the immunoprecipitated RNA (output).
2016-01-13 | E-GEOD-69856 | biostudies-arrayexpress
Project description:A prominent enzyme in organellar RNA metabolism is the exoribonuclease polynucleotide phosphorylase (PNPase), whose reversible activity is governed by the nucleotides diphosphate-inorganic phosphate ratio. In Chlamydomonas reinhardtii, PNPase regulates chloroplast transcript accumulation in response to phosphorus (P) starvation, and PNPase expression is repressed by the response regulator PSR1 under these conditions. Here, we investigated the role of PNPase in the Arabidopsis (Arabidopsis thaliana) P deprivation response by comparing wild-type and pnp mutant plants with respect to their morphology, metabolite profiles, and transcriptomes. We found that P-deprived pnp mutants develop aborted clusters of lateral roots, which are characterized by decreased auxin responsiveness and cell division, and exhibit cell death at the root tips. Electron microscopy revealed that the collapse of root organelles is enhanced in the pnp mutant under P deprivation and occurred with low frequency under P-replete conditions. Global analyses of metabolites and transcripts were carried out to understand the molecular bases of these altered P deprivation responses. We found that the pnp mutant expresses some elements of the deprivation response even when grown on a full nutrient medium, including altered transcript accumulation, although its total and inorganic P contents are not reduced. The pnp mutation also confers P status-independent responses, including but not limited to stress responses. Taken together, our data support the hypothesis that the activity of the chloroplast PNPase is involved in plant acclimation to P availability and that it may help maintain an appropriate balance of P metabolites even under normal growth conditions.
2009-09-12 | GSE18071 | GEO
Project description:A prominent enzyme in organellar RNA metabolism is the exoribonuclease polynucleotide phosphorylase (PNPase), whose reversible activity is governed by the nucleotides diphosphate-inorganic phosphate ratio. In Chlamydomonas reinhardtii, PNPase regulates chloroplast transcript accumulation in response to phosphorus (P) starvation, and PNPase expression is repressed by the response regulator PSR1 under these conditions. Here, we investigated the role of PNPase in the Arabidopsis (Arabidopsis thaliana) P deprivation response by comparing wild-type and pnp mutant plants with respect to their morphology, metabolite profiles, and transcriptomes. We found that P-deprived pnp mutants develop aborted clusters of lateral roots, which are characterized by decreased auxin responsiveness and cell division, and exhibit cell death at the root tips. Electron microscopy revealed that the collapse of root organelles is enhanced in the pnp mutant under P deprivation and occurred with low frequency under P-replete conditions. Global analyses of metabolites and transcripts were carried out to understand the molecular bases of these altered P deprivation responses. We found that the pnp mutant expresses some elements of the deprivation response even when grown on a full nutrient medium, including altered transcript accumulation, although its total and inorganic P contents are not reduced. The pnp mutation also confers P status-independent responses, including but not limited to stress responses. Taken together, our data support the hypothesis that the activity of the chloroplast PNPase is involved in plant acclimation to P availability and that it may help maintain an appropriate balance of P metabolites even under normal growth conditions.
2009-09-12 | GSE18071 | GEO
Project description:In all bacterial species examined thusfar, small regulatory RNAs (sRNAs) contribute to intricate patterns of genetic regulation. Many of the actions of these nucleic acids are mediated by chaperones such as the Hfq protein, and genetic screens have identified the exoribonuclease polynucleotide phosphorylase (PNPase) as a stabilizer and facilitator of sRNAs in vivo. We observe that the protective and facilitating effects of PNPase in vivo require the RNA-binding KH and S1 domains and the catalytic site, suggesting a requirement for physical interation of the ribonuclease with either the sRNA itself or other RNAs acting upstream of the process. Although purified PNPase can readily degrade sRNAs in vitro, those same substrates, as well as numerous other sRNAs and transcripts, can be co-purified from cells by immunoprecipitation with neither degradation nor modification to the 3’ end. Our results indicate that PNPase can bind RNA in two modes in vivo – either destructive or stabilizing, and that there is active flux of RNAs on PNPase so that the stable molecules do not accumulate. In the presence of Hfq, PNPase and sRNA form a ternary complex in which the enzyme plays a non-destructive, structural role, but the complex does not confer protection against the action of RNase E in vitro. Taken together, our results indicate that PNPase, Hfq and additional factors form a protective ribonucleoprotein assembly that stabilizes certain sRNAs and facilitates their activities.
2016-01-13 | GSE69856 | GEO
Project description:The polynucleotide phosphorylase (PNPase) is conserved among both Gram-positive and Gram-negative bacteria. As a core part of the degradosome, the PNPase is involved in maintaining proper RNA levels within the bacterial cell. It plays a major role in RNA homeostasis and decay since it acts as a 3’- to 5’-exoribonuclease. Furthermore PNPase can catalyze the reverse reaction by elongating RNA molecules in 5’- to 3’-end direction which finally has a destabilizing effect on the prolonged RNA molecule. RNA degradation can be initiated by an endonucleolytic cleavage and then by further promoted by exoribonucleolytic decay. In this study, we analyzed the importance of the Rhodobacter sphaeroides PNPase regarding the physiology and sRNA homeostasis. Moreover, we developed a pipeline to globally identify differential RNA 3’-ends in RNA NGS sequencing data obtained from PNPase, RNase E and RNase III mutants. The Rhodobacter sphaeroides PNPase mutant exhibits several phenotypical characteristics, including diminished adaption to low temperature, reduced resistance to organic peroxide induced stress and altered growth behavior. Furthermore, the transcriptome composition differs in the pnp mutant strain, resulting in a decreased abundance of most tRNAs and rRNAs. In addition, the PNPase has a major influence on the half-lives of several regulatory sRNAs and can have both a stabilizing or a destabilizing effect. The RNA 3’-end analysis reveals that 82% of all differential 3’-ends are enriched in the pnp mutant and are mostly located in coding sequences or untranslated regions (UTR). A fair percentage of these ends was also identified as differential RNA 3’-end in RNase E and RNase III mutant strains. The PNPase has a major influence in RNA processing and maturation and thus modulates the transcriptome. This includes regulatory sRNAs, stressing the role of PNPase in cellular homeostasis and its importance in regulatory networks. The 3’-end analysis indicates a sequential processing of UTR- and non-UTR derived sRNAs by several ribonucleases. Moreover, we provide a modular pipeline which greatly facilitates the identification of RNA 5’/3’-ends. It is publicly available on GitHub and is distributed under ICS licence.
2021-02-16 | GSE156818 | GEO
Project description:PNPase is the primary RNA turnover enzyme in Bacillus subtilis and plays a crucial role in regulating gene expression. To investigate the life activities that PNPase participated in Bacillus subtilis 9407, RNA immunoprecipitation-sequencing (RIP-seq) analysis was performed to pinpoint the direct RNA targets of PNPase using 6×his-tagged PNPase (PNPase group) and PNPaseD493A (D493A group) constructs that were driven by the IPTG-induced Pgrac promoter.
2023-09-20 | GSE243342 | GEO
Project description:Background The RNA steady-state levels in the cell are a balance between synthesis and degradation rates. Although transcription is important, RNA processing and turnover are also key factors in the regulation of gene expression. In Escherichia coli there are three main exoribonucleases (RNase II, RNase R and PNPase) involved in RNA degradation. Although there are many studies about these exoribonucleases not much is known about their global effect in the transcriptome. Results In order to study the effects of the exoribonucleases on the transcriptome, we sequenced the total RNA (RNA-Seq) from wild-type cells and from mutants for each of the exoribonucleases (∆rnb, ∆rnr and ∆pnp). We compared each of the mutant transcriptome with the wild-type to determine the global effects of the deletion of each exoribonucleases in exponential phase. We determined that the deletion of RNase II significantly affected 187 transcripts, while deletion of RNase R affects 202 transcripts and deletion of PNPase affected 226 transcripts. Surprisingly, many of the transcripts are actually down-regulated in the exoribonuclease mutants when compared to the wild-type control. The results obtained from the transcriptomic analysis pointed to the fact that these enzymes were changing the expression of genes related with flagellum assembly, motility and biofilm formation. The three exoribonucleases affected some stable RNAs, but PNPase was the main exoribonuclease affecting this class of RNAs. We confirmed by qPCR some fold-change values obtained from the RNA-Seq data, we also observed that all the exoribonuclease mutants were significantly less motile than the wild-type cells. Additionally, RNase II and RNase R mutants were shown to produce more biofilm than the wild-type control while the PNPase mutant did not form biofilms. Conclusions In this work we demonstrate how deep sequencing can be used to discover new and relevant functions of the exoribonucleases. We were able to obtain valuable information about the transcripts affected by each of the exoribonucleases and compare the roles of the three enzymes. Our results show that the three exoribonucleases affect cell motility and biofilm formation that are two very important factors for cell survival, especially for pathogenic cells.
2015-03-17 | GSE60107 | GEO
Project description:Exoribonucleases are crucial for RNA degradation in Escherichia coli but the roles of RNase R and PNPase and their potential overlap in stationary phase are not well characterized. Here, we used a genome-wide approach to determine how RNase R and PNPase affect the mRNA half-lives compared to wild type (stabilome) in the stationary phase. The stabilome is an original dynamic transcriptome-based analysis to measure the rates of mRNA degradation at the genome scale. We have combined the analysis of stabilome with the steady state concentrations of mRNAs (transcriptome) to provide an integrated overview of the in vivo activity of these exoribonucleases at the genome-scale. The stabilome demonstrated that the mRNAs are very stable in the stationary phase and that the deletion of RNase R or PNPase caused only a limited mRNA stabilization. Intriguingly the absence of PNPase provoked also the destabilization of many mRNAs. These changes in mRNA half-lives in the PNPase deletion strain were associated with a massive reorganization of mRNA levels and also variation in several ncRNA concentrations. Finally, the in vivo activity of the degradation machinery was found frequently saturated by mRNAs in the PNPase mutant unlike in the RNase R mutant, suggesting that the degradation activity is limited by the deletion of PNPase but not by the deletion of RNase R. This work allowed the roles of RNase R and PNPase in coordinating E. coli RNA metabolism to be discussed and PNPase to be identified as a central player of the degradation machinery in stationary phase.
2018-12-10 | GSE116577 | GEO