Genome-Wide Screens Reveal New Gene Products That Influence Genetic Competence in Streptococcus mutans

• Published in: Journal of bacteriology 2018-01, Vol.200 (2)
• Main Authors: Shields, Robert C, O'Brien, Greg, Maricic, Natalie, Kesterson, Alexandria, Grace, Megan, Hagen, Stephen J, Burne, Robert A
• Format: Article
• Language: English
• Subjects: Aberration; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; Biological activity; Cell division; Cues; Deoxyribonucleic acid; DNA; DNA Transformation Competence - physiology; Fluorescence; Fluorescence microscopy; Gene expression; Gene Expression Regulation, Bacterial - physiology; Genes; Genetics; Genome, Bacterial; Genome-Wide Association Study; Genomes; Gram-positive bacteria; Microscopy; Mutants; Mutation; Peptides; Ribonucleic acid; RNA; Screens; Sigma factor; Signal peptides; Signaling; Spotlight; Streptococcus infections; Streptococcus mutans; Streptococcus mutans - genetics; Streptococcus mutans - metabolism; Transcription activation; Transposon mutagenesis; Transposons
• ISSN: 0021-9193; 1098-5530
• DOI: 10.1128/JB.00508-17

A network of genes and at least two peptide signaling molecules tightly control when becomes competent to take up DNA from its environment. Widespread changes in the expression of genes occur when is presented with competence signal peptides , including the increased production of the alternative sigma factor, ComX, which activates late competence genes. Still, the way that gene products that are regulated by competence peptides influence DNA uptake and cellular physiology are not well understood. Here, we developed and employed comprehensive transposon mutagenesis of the genome, with a screen to identify mutants that aberrantly expressed , coupled with transposon sequencing (Tn-seq) to gain a more thorough understanding of the factors modulating expression and progression to the competent state. The screens effectively identified genes known to affect competence, e.g., , , , , , , , and , but disclosed an additional 20 genes that were not previously competence associated. The competence phenotypes of mutants were characterized, including by fluorescence microscopy to determine at which stage the mutants were impaired for activation. Among the novel genes studied were those implicated in cell division, the sensing of cell envelope stress, cell envelope biogenesis, and RNA stability. Our results provide a platform for determining the specific chemical and physical cues that are required for genetic competence in , while highlighting the effectiveness of using Tn-seq in to discover and study novel biological processes. acquires DNA from its environment by becoming genetically competent, a physiologic state triggered by cell-cell communication using secreted peptides. Competence is important for acquiring novel genetic traits and has a strong influence on the expression of virulence-associated traits of Here, we used transposon mutagenesis and genomic technologies to identify novel genes involved in competence development. In addition to identifying genes previously known to be required for expression, 20 additional genes were identified and characterized. The findings create opportunities to diminish the pathogenic potential of , while validating technologies that can rapidly advance our understanding of the physiology, biology, and genetics of and related pathogens.