Suppressor mutations in ribosomal proteins and FliY restore Bacillus subtilis swarming motility in the absence of EF-P [Ribosome Profiling]
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ABSTRACT: 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.
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: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.
Project description:Ribosome profiling is a powerful method for globally assessing the activity of ribosomes in a cell. Despite its application in many organisms, ribosome profiling studies in bacteria have struggled to obtain the resolution necessary to precisely define translational pauses. Here we report improvements that yield much higher resolution in E. coli profiling data, enabling us to more accurately assess ribosome pausing and refine earlier studies of the impact of polyproline motifs on elongation. We comprehensively characterize pausing at proline-rich motifs in the absence of elongation factor EFP. We find that only a small fraction of genes with strong pausing motifs have reduced ribosome density downstream and identify features that explain this phenomenon. These features allow us to predict which proteins likely have reduced output in the efp knockout strain. Ribosome profiling of E. coli MG1655 and mutants lacking EFP or its three modifiying enzymes
Project description:Ribosome profiling is a powerful method for globally assessing the activity of ribosomes in a cell. Despite its application in many organisms, ribosome profiling studies in bacteria have struggled to obtain the resolution necessary to precisely define translational pauses. Here we report improvements that yield much higher resolution in E. coli profiling data, enabling us to more accurately assess ribosome pausing and refine earlier studies of the impact of polyproline motifs on elongation. We comprehensively characterize pausing at proline-rich motifs in the absence of elongation factor EFP. We find that only a small fraction of genes with strong pausing motifs have reduced ribosome density downstream and identify features that explain this phenomenon. These features allow us to predict which proteins likely have reduced output in the efp knockout strain.
Project description:Suppressor mutations in ribosomal proteins and FliY restore Bacillus subtilis swarming motility in the absence of EF-P [Ribosome Profiling]
Project description:Purpose: Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that undergoes swarming motility in response to semisolid conditions with amino acids as a nitrogen source. With a genome encoding hundreds of potential intergenic small RNAs (sRNAs), P. aeruginosa can easily adapt to different conditions and stresses. We previously identified 20 sRNAs dysregulated under swarming conditions and here provide phenotypic characterization for these sRNAs. Methods: Here, these sRNA were overexpressed in strain PAO1 and subjected to an array of phenotypic screens. Results: Overexpression of prrH resulted in decreased swimming motility, while a ∆prrH mutant had decreased cytotoxicity and increased pyoverdine production. Overexpression of the previously uncharacterized PA2952.1 resulted in decreased swarming and swimming motility, increased gentamicin and tobramycin resistance under swarming conditions, and increased trimethoprim susceptibility. RNA-Seq and proteomics were performed on the wildtype overexpressing PA2952.1 cf. the empty vector control under swarming conditions, and revealed the differential expression of 784 genes and differential abundance of 445 proteins. Amongst these were found 82 transcriptional regulators, two-component systems, sigma and anti-sigma factors. Downstream effectors included downregulated pili, dysregulated flagellar genes, the upregulated efflux pump MexGHI-OpmD, the upregulated arn operon, and downregulated DNA synthesis genes. Genes involved in iron and zinc uptake were also dysregulated, and certain pyoverdine and phenazine genes were upregulated. Conclusions: Overall, the sRNAs PA2952.1 and prrH appeared to be involved in regulating virulence-related programs in P. aeruginosa, including iron acquisition and motility.
Project description:We have exploited a spontaneously isolated mutant IgaA(T191P) that is near-maximally activated for the Rcs system, to identify a vast set of genes that respond, and report new regulatory properties of this signaling system in Salmonella enterica serovar Typhimurium. Microarray data show that the Rcs system normally functions as a positive regulator of SPI-2 and other genes important for growth of Salmonella in macrophages, although when highly activated, the system completely represses the SPI-1/SPI-2 virulence, flagellar, and fimbrial biogenesis pathways. The auxilliary protein RcsA, which works with RcsB to positively regulate colanic acid and other target genes, not only stimulates but also antagonizes the positive regulation of many genes in the igaA mutant. We show that RcsB represses motility through the 'RcsB box' in the promoter region of the master operon flhDC, and that RcsA is not required for this regulation. Curiously, RcsB selectively stimulates expression of the flagellar Type 3 secretion genes fliPQR; an RcsAB box located downstream of fliR influences this regulation. We show that excess colanic acid impairs swimming and inhibits swarming motility, consistent with the inverse regulation of the two pathways by the Rcs system. The work was published in Journal of Bacteriology: Wang Q, Zhao Y, McClelland M, Harshey RM. The RcsCDB signaling system and swarming motility in Salmonella enterica serovar Typhimurium: dual regulation of flagellar and SPI-2 virulence genes. J Bacteriol. 2007 Sep 28; [Epub ahead of print] PMID: 17905992 [PubMed - as supplied by publisher] Keywords: Comparative genomic hybridization
Project description:Many bacteria convert bicyclic compounds, such as indole and naphthalene, to oxidized compounds, including hydroxyindoles and naphthols. Pseudomonas aeruginosa, a ubiquitous bacterium that inhabits diverse environments, shows pathogenicity against animals, plants and other microorganisms, and increasing evidence has shown that several bicyclic compounds alter the virulence-related phenotypes of P. aeruginosa. Here, we revealed that hydroxyindoles (4- and 5-hydroxyindoles) and naphthalene derivatives bearing hydroxyl groups specifically inhibit swarming motility but have minor effects on other motilities, including swimming and twitching, in P. aeruginosa. Further analyses using 1-naphthol showed that this effect is also associated with clinically isolated hyper swarming P. aeruginosa cells. Swarming motility is associated with the dispersion of cells from biofilms, and the addition of 1-naphthol maintained biofilm biomass without cell dispersion. Swarming inhibition did not mediate rhamnolipid production, which regulates swarming motility in P. aeruginosa. Transcriptome analyses revealed that 1-naphthol increases gene expression associated with multidrug efflux and represses gene expression associated with aerotaxis and pyochelin, flagellar, and pili synthesis. In the present study, we showed that several bicyclic compounds bearing hydroxyl groups inhibit the swarming motility of P. aeruginosa, and these results provide new insight into the chemical structures that inhibit the specific phenotypes of P. aeruginosa.
Project description:Many bacteria convert bicyclic compounds, such as indole and naphthalene, to oxidized compounds, including hydroxyindoles and naphthols. Pseudomonas aeruginosa, a ubiquitous bacterium that inhabits diverse environments, shows pathogenicity against animals, plants and other microorganisms, and increasing evidence has shown that several bicyclic compounds alter the virulence-related phenotypes of P. aeruginosa. Here, we revealed that hydroxyindoles (4- and 5-hydroxyindoles) and naphthalene derivatives bearing hydroxyl groups specifically inhibit swarming motility but have minor effects on other motilities, including swimming and twitching, in P. aeruginosa. Further analyses using 1-naphthol showed that this effect is also associated with clinically isolated hyper swarming P. aeruginosa cells. Swarming motility is associated with the dispersion of cells from biofilms, and the addition of 1-naphthol maintained biofilm biomass without cell dispersion. Swarming inhibition did not mediate rhamnolipid production, which regulates swarming motility in P. aeruginosa. Transcriptome analyses revealed that 1-naphthol increases gene expression associated with multidrug efflux and represses gene expression associated with aerotaxis and pyochelin, flagellar, and pili synthesis. In the present study, we showed that several bicyclic compounds bearing hydroxyl groups inhibit the swarming motility of P. aeruginosa, and these results provide new insight into the chemical structures that inhibit the specific phenotypes of P. aeruginosa. In total 4 samples: gene expressions of P. aeruginosa with (2 samples) or without (2 samples) 1-naphthol