title: Pseudomonas aeruginosa biofilm matrix polysaccharide Psl is regulated transcriptionally by RpoS and post-transcriptionally by RsmA.
abstract: Extracellular polysaccharides are important components of biofilms. In non-mucoid Pseudomonas aeruginosa strains, the Pel and Psl polysaccharides are major structural components of the biofilm matrix. In this study, we demonstrate that the alternative σ-factor RpoS is a positive transcriptional regulator of psl gene expression. Furthermore, we show that psl mRNA has an extensive 5' untranslated region, to which the post-transcriptional regulator RsmA binds and represses psl translation. Our observations suggest that upon binding RsmA, the region spanning the ribosome binding site of psl mRNA folds into a secondary stem-loop structure that blocks the Shine-Dalgarno sequence, preventing ribosome access and protein translation. This constitutes a novel mechanism for translational repression by this family of regulators.
authors.affiliation: Department of Microbiology, University of Washington, Seattle, WA 98195, USA.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Irie
authors.forename: Melissa
authors.initials: M
authors.lastname: Starkey
authors.forename: Adrianne N
authors.initials: AN
authors.lastname: Edwards
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Wozniak
authors.forename: Tony
authors.initials: T
authors.lastname: Romeo
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Parsek
mesh_terms: D020121:5' Untranslated Regions; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D018441:Biofilms; D015964:Gene Expression Regulation, Bacterial; D009876:Operon; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000378:metabolism; D012329:RNA, Bacterial / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D024363:Transcription Initiation Site
chemical_list: D020121:5' Untranslated Regions; D001426:Bacterial Proteins; D011135:Polysaccharides, Bacterial; D012329:RNA, Bacterial; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; D012808:Sigma Factor; C069567:sigma factor KatF protein, Bacteria