title: Targeting of csgD by the small regulatory RNA RprA links stationary phase, biofilm formation and cell envelope stress in Escherichia coli.
abstract: RprA is a small regulatory RNA known to weakly affect the translation of σ(S)  (RpoS) in Escherichia coli. Here we demonstrate that csgD, which encodes a stationary phase-induced biofilm regulator, as well as ydaM, which encodes a diguanylate cyclase involved in activating csgD transcription, are novel negatively controlled RprA targets. As shown by extensive mutational analysis, direct binding of RprA to the 5'-untranslated and translational initiation regions of csgD mRNA inhibits translation and reduces csgD mRNA levels. In the case of ydaM mRNA, RprA base-pairs directly downstream of the translational start codon. In a feedforward loop, RprA can thus downregulate > 30 YdaM/CsgD-activated genes including those for adhesive curli fimbriae. However, during early stationary phase, when csgD transcription is strongly activated, the synthesis of csgD mRNA exceeds that of RprA, which allows the accumulation of CsgD protein. This situation is reversed when csgD transcription is shut off - for instance, later in stationary phase or during biofilm formation - or by conditions that further activate RprA expression via the Rcs two-component system. Thus, antagonistic regulation of csgD and RprA at the mRNA level integrates cell envelope stress signals with global gene expression during stationary phase and biofilm formation.
authors.affiliation: Institut für Biologie - Mikrobiologie, Freie Universität Berlin, 14195 Berlin, Germany.
authors.forename: Franziska
authors.initials: F
authors.lastname: Mika
authors.forename: Susan
authors.initials: S
authors.lastname: Busse
authors.forename: Alexandra
authors.initials: A
authors.lastname: Possling
authors.forename: Janine
authors.initials: J
authors.lastname: Berkholz
authors.forename: Natalia
authors.initials: N
authors.lastname: Tschowri
authors.forename: Nicole
authors.initials: N
authors.lastname: Sommerfeldt
authors.forename: Mihaela
authors.initials: M
authors.lastname: Pruteanu
authors.forename: Regine
authors.initials: R
authors.lastname: Hengge
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D001665:Binding Sites; D018441:Biofilms / Q000254:growth & development*; D002473:Cell Wall / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D019761:Phosphorus-Oxygen Lyases / Q000235:genetics / Q000378:metabolism; D014176:Protein Biosynthesis; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D018085:Regulon; D012808:Sigma Factor / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; C499694:CsgD protein, E coli; D029968:Escherichia coli Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D012808:Sigma Factor; D015534:Trans-Activators; C069567:sigma factor KatF protein, Bacteria; C077481:Crl protein, Bacteria; D019761:Phosphorus-Oxygen Lyases; C517137:YdaM protein, E coli