csrR, a Paralog and Direct Target of CsrA, Promotes Legionella pneumophila Resilience in Water

摘要: ABSTRACT Critical to microbial versatility is the capacity express cohort of genes that increase fitness in different environments. Legionella pneumophila occupies extensive ecological space includes diverse protists, pond water, engineered water systems, and mammalian lung macrophages. One mechanism equips this opportunistic pathogen adapt fluctuating conditions a switch between replicative transmissive cell types controlled by broadly conserved regulatory protein CsrA. A striking feature legionellae surveyed each 14 strains encodes 4 7 csrA -like genes, candidate regulators distinct traits. Here we focus on one paralog ( lpg1593 ) that, like canonical , all surveyed. Phenotypic analysis revealed long-term survival tap promoted locus, which name csrR (for “CsrA-similar for resilience”). As predicted its GGA motif, mRNA was bound directly CsrA protein, as judged electromobility shift RNA-footprinting assays. Furthermore, repressed translation vivo determined csrR-gfp reporters, stability presence absence expression, mutation binding site identified mRNA. Thus, not only governs transition from replication transmission but also represses when nutrients are available. We propose during prolonged starvation, relief repression permits CsrR coordinate L. pneumophila9s type resilient supplies. IMPORTANCE Persistence systems public health risk, yet there little understanding genetic determinants equip survive natural or systems. potent regulator pathogen9s intracellular life cycle CsrA, widely distributed among bacterial species understood quite well. Our finding every sequenced strain carries several paralogs—including two common isolates—indicates exploit switches multiple purposes. discovery paralog, CsrR, target enhances an important step toward colonization environment pathogenic pneumophila.