Elongation Factor P is important for sporulation initiation
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ABSTRACT: The universally conserved protein Elongation Factor P facilitates translation at amino acids that form peptide bonds with low efficiency, particularly poly-proline tracts. Despite its wide conservation, it is not essential in most bacteria and its physiological role remains unclear. Here, we show that EF-P affects the process of sporulation initiation in the bacterium Bacillus subtilis. We observe that lack of EF-P delays expression of sporulation-specific genes. Using ribosome profiling, we observe that expression of spo0A, encoding a transcription factor that functions as the master regulator of sporulation, is lower in a ∆efp strain as compared to the wildtype. Ectopic expression of Spo0A rescues the sporulation initiation phenotype, indicating that reduced spo0A expression explains the sporulation defect in ∆efp cells. Since Spo0A is the earliest sporulation transcription factor, these data suggest that sporulation initiation can be delayed when protein synthesis is impaired.
ORGANISM(S): Bacillus subtilis subsp. subtilis str. 168
Project description:Purpose: The goal of this study was to identify genes whose expression is induced during sporulation in a Spo0A-, σF-, σE-, σG-, and σK-dependent manner. Methods: Whole genome RNA sequencing was performed on wildtype, spo0A-, sigF-, sigE-, sigG-, and sigK- C. difficile strains (strain 630 background; JIR8094 = parent strain), and the transcriptional profiles of the different mutants during growth on 70:30 agar plates were determined using an Illumina HiSeq1000. Results: This analysis identified 185 genes whose expression is collectively activated by sporulation sigma factors: 150 were σF-dependent, 150 were σE-dependent, 30 were σG-dependent, and 31 were σK-dependent. A total of 237 genes were identified as requiring Spo0A for their expression when sporulation was induced on the 70:30 plates. Conclusions: These results provide the first genome-wide transcriptional analysis of genes whose expression is induced by specific sporulation sigma factors in the Clostridia and highlight that diverse mechanisms regulate sporulation sigma factor activity in the Firmicutes. For example, in contrast with the B. subtilis sporulation pathway, C. difficile σE was not required to fully activate σG, and σG was not required to activate σK.
Project description:Protein synthesis is performed by the ribosome and a host of highly conserved elongation factors. Elongation factor P (EF-P) prevents ribosome stalling at difficult-to-translate sequences, particularly polyproline tracts. In bacteria, phenotypes associated with efp deletion range from modest to lethal, suggesting that some species encode an additional translation factor that has similar function to EF-P. Here we identify YfmR as a translation factor that is essential in the absence of EF-P in B. subtilis. YfmR is an ABCF ATPase that is closely related to both Uup and EttA, ABCFs that bind the ribosomal E-site and are conserved in more than 50% of bacterial genomes. We show that YfmR associates with actively translating ribosomes, and that depleting YfmR from ∆efp cells causes severe ribosome stalling at a polyproline tract in vivo. YfmR depletion from ∆efp cells was lethal, and caused reduced levels of actively translating ribosomes. Our results therefore identify YfmR as an important translation factor that is essential in B. subtilis in the absence of EF-P.
Project description:Purpose: The goal of this study was to identify genes whose expression is induced during sporulation in a Spo0A-, M-OM-^CF-, M-OM-^CE-, M-OM-^CG-, and M-OM-^CK-dependent manner. Methods: Whole genome RNA sequencing was performed on wildtype, spo0A-, sigF-, sigE-, sigG-, and sigK- C. difficile strains (strain 630 background; JIR8094 = parent strain), and the transcriptional profiles of the different mutants during growth on 70:30 agar plates were determined using an Illumina HiSeq1000. Results: This analysis identified 185 genes whose expression is collectively activated by sporulation sigma factors: 150 were M-OM-^CF-dependent, 150 were M-OM-^CE-dependent, 30 were M-OM-^CG-dependent, and 31 were M-OM-^CK-dependent. A total of 237 genes were identified as requiring Spo0A for their expression when sporulation was induced on the 70:30 plates. Conclusions: These results provide the first genome-wide transcriptional analysis of genes whose expression is induced by specific sporulation sigma factors in the Clostridia and highlight that diverse mechanisms regulate sporulation sigma factor activity in the Firmicutes. For example, in contrast with the B. subtilis sporulation pathway, C. difficile M-OM-^CE was not required to fully activate M-OM-^CG, and M-OM-^CG was not required to activate M-OM-^CK. Wildtype, spo0A-, sigF-, sigE-, sigG-, and sigK- were streaked onto 70:30 plates in triplicate, and sporulation was induced. RNA from the three biological replicate samples was harvested, DNAse-I treated, and ribosomally depleted using Ribo-Zero kits. This RNA was transformed into cDNA, and the resulting libraries were subjected to paired end sequencing using an Illumina HiSeq 1000.
Project description:Clostridium acetobutylicum, the endospore-forming anaerobe best known for its ABE (acetone-butanol-ethanol) fermentation, has received renewed attention recently for the biological production of butanol, both for bulk chemical production and as a potential biofuel. With butanol production in mind, most of the recent research on C. acetobutylicum has focused on increasing butanol production, tolerance to butanol, and optimizing it for various substrates. However, an equally important trait, though less understood, is its sporulation program, which it coupled to solvent formation. The model organism for endospore formation is Bacillus subtilis, but significant physiological, metabolic, and genomic differences exist between the two organisms. Despite these differences, the major sporulation-related transcription/sigma factors are conserved between the two species. These transcription/sigma factors are activated in a cascade manner such that Spo0A becomes active first, followed by σF, then σE, then σG, and finally σK. The goal of this study is to determine the regulons of 4 of these transcription/sigma factors (Spo0A, σF, σE, and σG) and compare them to those in B. subtilis. To accomplish this goal, individual mutant strains were created for Spo0A, σF, σE, and σG, in which the transcription/sigma factor is silenced. These mutants were then compared transcriptionally using microarrays to determine the regulon of each transcription/sigma factor. To help avoid false positives, comparisons were made between strains in which the downstream transcription/sigma factor is silenced (e.g., for the Spo0A regulon, the Spo0A mutant was compared against the σF mutant and the σE mutant, since they are both upregulated by Spo0A) rather than just the WT. For each regulon, 4 timepoints were taken, since it is very difficult to synchronize sporulation in C. acetobutylicum cultures, and dye-swaps were prepared for each timepoint.
Project description:The obligate anaerobic, enteric pathogen Clostridioides difficile persists in the intestinal tract by forming antibiotic resistant endospores that contribute to relapsing and recurrent infections. Despite the importance of sporulation for C. difficile pathogenesis, environmental cues, and molecular mechanisms regulating sporulation initiation remain ill defined. Here, using RIL-seq to capture the Hfq-dependent RNA-RNA interactome, we discovered a network of small RNAs that bind to mRNAs encoding sporulation-related genes. We show that two of these small RNAs, SpoX and SpoY, regulate translation of the master regulator of sporulation, Spo0A, in an opposing manner, which ultimately leads to altered sporulation rates. Infection of antibiotic-treated mice with SpoX and SpoY deletion mutants revealed a global effect on gut colonization and intestinal sporulation. Our work uncovers an elaborate RNA-RNA interactome controlling the physiology and virulence of C. difficile and identifies a complex post-transcriptional layer in the regulation of spore formation in this important human pathogen.
Project description:Clostridium acetobutylicum, the endospore-forming anaerobe best known for its ABE (acetone-butanol-ethanol) fermentation, has received renewed attention recently for the biological production of butanol, both for bulk chemical production and as a potential biofuel. With butanol production in mind, most of the recent research on C. acetobutylicum has focused on increasing butanol production, tolerance to butanol, and optimizing it for various substrates. However, an equally important trait, though less understood, is its sporulation program, which it coupled to solvent formation. The model organism for endospore formation is Bacillus subtilis, but significant physiological, metabolic, and genomic differences exist between the two organisms. Despite these differences, the major sporulation-related transcription/sigma factors are conserved between the two species. These transcription/sigma factors are activated in a cascade manner such that Spo0A becomes active first, followed by M-OM-^CF, then M-OM-^CE, then M-OM-^CG, and finally M-OM-^CK. The goal of this study is to determine the regulons of 4 of these transcription/sigma factors (Spo0A, M-OM-^CF, M-OM-^CE, and M-OM-^CG) and compare them to those in B. subtilis. To accomplish this goal, individual mutant strains were created for Spo0A, M-OM-^CF, M-OM-^CE, and M-OM-^CG, in which the transcription/sigma factor is silenced. These mutants were then compared transcriptionally using microarrays to determine the regulon of each transcription/sigma factor. To help avoid false positives, comparisons were made between strains in which the downstream transcription/sigma factor is silenced (e.g., for the Spo0A regulon, the Spo0A mutant was compared against the M-OM-^CF mutant and the M-OM-^CE mutant, since they are both upregulated by Spo0A) rather than just the WT. For each regulon, 4 timepoints were taken, since it is very difficult to synchronize sporulation in C. acetobutylicum cultures, and dye-swaps were prepared for each timepoint. Four transcription/sigma factor regulons were investigated: Spo0A, M-OM-^CF, M-OM-^CE, and M-OM-^CG. For Spo0A, two comparison were made: Spo0A mutant vs M-OM-^CF mutant and Spo0A mutant vs M-OM-^CE mutant. For M-OM-^CF, two comparison were also made: M-OM-^CF mutant vs M-OM-^CE mutant and M-OM-^CF mutant vs M-OM-^CG mutant. Finally for M-OM-^CE and M-OM-^CG, only one comparison for each was made: M-OM-^CE mutant vs M-OM-^CG mutant and M-OM-^CG mutant vs wild-type, respectively. For each comparison, 4 timepoints were analyzed, and dye-swaps were prepared for each timepoint comparison. Timepoints were chosen based on when each transcription/sigma factor was expected to be active, based on a previous study [Jones, SW, et al. Genome Biol. 2008;9(7):R114.].
Project description:Purpose: A goal of this study was to identify genes induced in the mother cell during Clostridium difficile sporulation (specifically in a σE-, σK-, and SpoIIID-dependent manner). Methods: Whole genome RNA sequencing was performed on wildtype, sigE-, sigK- and spoIIID- C. difficile strains (strain 630 background; JIR8094 = parent strain), and the transcriptional profiles of the different mutants during growth on 70:30 agar plates were determined using an Illumina MiSeq1000. Results: This analysis identified 200 genes whose expression is collectively activated by sporulation sigma factors: 159 were σF-dependent, 162 were σE-dependent, 28 were σG-dependent, and 36 were σK-dependent. A total of 254 genes were identified as requiring Spo0A for their expression when sporulation was induced on the 70:30 plates. Conclusions: These results provide the first genome-wide transcriptional analysis of genes whose expression is induced by specific sporulation sigma factors in the Clostridia and highlight that diverse mechanisms regulate sporulation sigma factor activity in the Firmicutes. For example, in contrast with the B. subtilis sporulation pathway, C. difficile σE was not required to fully activate σG, and σG was not required to activate σK.
Project description:Translation elongation factor P (EF-P) alleviates ribosome pausing at a subset of motifs encoding consecutive proline residues and is required for growth in many organisms. Here we show that Bacillus subtilis EF-P also alleviated ribosome pausing at sequences encoding tandem prolines, and ribosomes paused within several essential genes without a corresponding growth defect in an efp mutant. The B. subtilis efp mutant is instead impaired for flagellar biosynthesis which results in the abrogation of a form of motility called swarming. We isolate swarming suppressors of efp and identify mutations in 8 genes that suppressed the efp mutant swarming defect, many of which encode conserved ribosomal proteins or ribosome-associated factors. One mutation abolished a translational pause site within the flagellar C-ring component FliY to increase flagellar number and restore swarming motility in the absence of EF-P. Our data support a model wherein EF-P-alleviation of ribosome pausing may be particularly important for macromolecular assemblies like the flagellum that require precise protein stoichiometries.
Project description:Translation elongation factor P (EF-P) alleviates ribosome pausing at a subset of motifs encoding consecutive proline residues and is required for growth in many organisms. Here we show that Bacillus subtilis EF-P also alleviated ribosome pausing at sequences encoding tandem prolines, and ribosomes paused within several essential genes without a corresponding growth defect in an efp mutant. The B. subtilis efp mutant is instead impaired for flagellar biosynthesis which results in the abrogation of a form of motility called swarming. We isolate swarming suppressors of efp and identify mutations in 8 genes that suppressed the efp mutant swarming defect, many of which encode conserved ribosomal proteins or ribosome-associated factors. One mutation abolished a translational pause site within the flagellar C-ring component FliY to increase flagellar number and restore swarming motility in the absence of EF-P. Our data support a model wherein EF-P-alleviation of ribosome pausing may be particularly important for macromolecular assemblies like the flagellum that require precise protein stoichiometries.