Teg58, a Small Regulatory RNA Repressed by SarA, is In-volved in Regulation of Arginine Biosynthesis and Biofilm Formation in Staphylococcus aureus
Staphylococcus aureus adapts to different environments by sensing and responding to diverse environmental cues.  The responses are coordinately regulated by regula-tory proteins, and small regulatory RNAs (sRNAs) at the transcriptional and/or translational levels. Here, we have characterized Teg58, a SarA repressed sRNA, using ChIP-Seq with SarA and RNA-Seq analysis of a sarA mutant pair in SH1000 and JE2 genetic backgrounds.  Phenotypic and genetic analyses indicated that inacti-vation of Teg58 led to reduced biofilm formation in a process that is independent of previously known biofilm modulating gene products such as SarA, agr, PIA, and PSMs.  RNA-Seq analysis of isogenic Teg58 mutant revealed up-regulation of argi-nine biosynthesis genes (i.e., argGH) as well as the ability of the mutant to grow in a chemical defined medium (CDM) lacking L-arginine vs. the parental strain/complemented mutant.  Further analysis both in vitro and in vivo demonstrated that repression of arginine synthesis by Teg58 occurred at the post-transcriptional level via specific interaction between Teg58 and the argGH mRNA. Exogenous argi-nine or endogenous induction of argGH led to a decrease in biofilm formation in pa-rental strains.  In addition, biochemical and genetic analyses of various arginine cat-abolic pathway genes demonstrated that the catabolic pathway is not involved in re-duced biofilm formation in the Teg58 mutant. Overall, our analyses suggest that Teg58 is a regulatory sRNA that plays an important role in augmenting biofilm for-mation via repression of arginine biosynthesis in S. aureus.