title: The Crc and Hfq proteins of Pseudomonas putida cooperate in catabolite repression and formation of ribonucleic acid complexes with specific target motifs.
abstract: The Crc protein is a global regulator that has a key role in catabolite repression and optimization of metabolism in Pseudomonads. Crc inhibits gene expression post-transcriptionally, preventing translation of mRNAs bearing an AAnAAnAA motif [the catabolite activity (CA) motif] close to the translation start site. Although Crc was initially believed to bind RNA by itself, this idea was recently challenged by results suggesting that a protein co-purifying with Crc, presumably the Hfq protein, could account for the detected RNA-binding activity. Hfq is an abundant protein that has a central role in post-transcriptional gene regulation. Herein, we show that the Pseudomonas putida Hfq protein can recognize the CA motifs of RNAs through its distal face and that Crc facilitates formation of a more stable complex at these targets. Crc was unable to bind RNA in the absence of Hfq. However, pull-down assays showed that Crc and Hfq can form a co-complex with RNA containing a CA motif in vitro. Inactivation of the hfq or the crc gene impaired catabolite repression to a similar extent. We propose that Crc and Hfq cooperate in catabolite repression, probably through forming a stable co-complex with RNAs containing CA motifs to result in inhibition of translation initiation.
authors.affiliation: Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Darwin 3, Cantoblanco, 28049, Madrid, Spain.
authors.forename: Renata
authors.initials: R
authors.lastname: Moreno
authors.forename: Sofía
authors.initials: S
authors.lastname: Hernández-Arranz
authors.forename: Ruggero
authors.initials: R
authors.lastname: La Rosa
authors.forename: Luis
authors.initials: L
authors.lastname: Yuste
authors.forename: Anjana
authors.initials: A
authors.lastname: Madhushani
authors.forename: Victoria
authors.initials: V
authors.lastname: Shingler
authors.forename: Fernando
authors.initials: F
authors.lastname: Rojo
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D057465:Catabolite Repression / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D035001:Host Factor 1 Protein / Q000378:metabolism*; D059372:Nucleotide Motifs; D016958:Pseudomonas putida / Q000235:genetics* / Q000378:metabolism; D012329:RNA, Bacterial / Q000737:chemistry / Q000378:metabolism*; D012333:RNA, Messenger / Q000737:chemistry / Q000378:metabolism; D058727:RNA, Small Untranslated / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D035001:Host Factor 1 Protein; D012329:RNA, Bacterial; D012333:RNA, Messenger; D058727:RNA, Small Untranslated; D012097:Repressor Proteins; C101896:crc protein, Pseudomonas