Sortase A-mediated modification of the Streptococcus mutans transcriptome and virulence traits

This study investigated the effects of srtA deletion on Streptococcus mutans (S.mutans) virulence determinants (acid tolerance, acid production and glucangeneration) and genome transcription. We used phenotype experiments, includingacid killing assays, glycolytic rate assessments and exopolysaccharide (EPS)formation tests, to detect whether srtA deletion influenced S. mutans acidtolerance/production and glucan formation. Additionally, RNA-sequencing was usedFfor transcriptomic analysis, and comparisons between sequencing data from both theexponential and stationary r phases of UA159 and the srtA-deleted strain were made todetermine the impact of srtA knockout on S. mutans genome transcription. The resulteof the phenotype assays indicated that srtA deletion enhanced S. mutans aciduricityiwhen bacterial cells were directly e subjected to pH 2.8, but the enhancement wasrepressed when the acid tolerance response of S. mutans strains was induced inadvance. The srtA mutation decreased EPS formation O of S. mutans in mature biofilms.No alteration was found in the glycolytic rate due to the l loss of srtA. SrtA deletion ledto pleiotropic changes in the S. mutans transcriptome with a phase-dependent pattern.The affected genes in S. mutans mainly included aciduricity, carbohydrate transportand EPS formation. It was concluded that S. mutans srtA had multiple effects on thevirulence traits of this pathogen, including acid tolerance and glucan formation, andthat these alterations could be partially due to transcriptional changes upon loss ofsrtA. SrtA deletion had pleiotropic effects on the S. mutans transcriptome, and theseeffects were growth phase dependent.