The C-terminal region of the RNA helicase CshA is required for the interaction with the degradosome and turnover of bulk RNA in the opportunistic pathogen Staphylococcus aureus.. Staphylococcus aureus

Staphylococcus aureus is a versatile opportunistic pathogen that adapts readily to a variety of different growth conditions. This adaptation requires a rapid regulation of gene expression including the control of mRNA abundance. The CshA DEAD-box RNA helicase was previously shown to be required for efficient turnover of the agr quorum sensing mRNA. Here we show by transcriptome-wide RNA sequencing and microarray analyses that CshA is required for the degradation of bulk mRNA. Moreover a subset of mRNAs is significantly stabilised in absence of CshA. Deletion of the C-terminal extension affects RNA turnover similar to the full deletion of the cshA gene. In accordance with RNA decay data, the C-terminal region of CshA is required for an RNA-independent interaction with components of the RNA degradation machinery. The C-terminal truncation of CshA reduces its ATPase activity and this reduction cannot be compensated at high RNA concentrations. Finally, the deletion of the C-terminal extension does affect growth at low temperatures, but to a significantly lesser degree than the full deletion, indicating that the core of the helicase can assume a partial function and opening the possibility that CshA is involved in different cellular processes. Overall design: 2 CshA mutants and a WT strain are prepared in duplicate for RNA decay assay. A time course after rifampicin treatment is performed on each preparation sampling at 4 time points: t=0s, t=150s, t=300s, t=600s. All samples are submitted for RNA-seq.