title: The Pseudomonas putida Crc global regulator is an RNA binding protein that inhibits translation of the AlkS transcriptional regulator.
abstract: The Crc protein is a global regulator that controls the hierarchical assimilation of carbon sources in Pseudomonads by inhibiting expression of several catabolic pathways. Crc does not bind DNA and its mechanism of action has remained elusive. Among other genes, Crc inhibits expression of alkS, the transcriptional activator of the Pseudomonas putida OCT plasmid alkane degradation pathway. AlkS activates expression of its own gene. In the presence of saturating AlkS levels, translational fusions of alkS to the lacZ reporter gene were responsive to Crc, but transcriptional fusions were not. In translational fusions, the first 33 nt of alkS mRNA, which includes up to position +3 relative to the translation start site, were sufficient to confer an efficient response to Crc. In vitro, purified Crc could bind specifically to an alkS mRNA fragment spanning positions +1 to +43, comprising the translation initiation region. We have previously shown that Crc has little effect on the stability of alkS mRNA. We conclude that Crc modulates AlkS levels by binding to the translation initiation region of alkS mRNA, thereby inhibiting translation. Because AlkS is an unstable protein present in limiting amounts, reducing its levels leads to decreased expression of all genes in the pathway.
authors.affiliation: Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Campus de la Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
authors.forename: Renata
authors.initials: R
authors.lastname: Moreno
authors.forename: Ana
authors.initials: A
authors.lastname: Ruiz-Manzano
authors.forename: Luis
authors.initials: L
authors.lastname: Yuste
authors.forename: Fernando
authors.initials: F
authors.lastname: Rojo
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D007763:Lac Operon / Q000235:genetics; D008954:Models, Biological; D008957:Models, Genetic; D009876:Operon / Q000235:genetics; D011485:Protein Binding; D014176:Protein Biosynthesis / Q000235:genetics*; D016958:Pseudomonas putida / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; C101896:crc protein, Pseudomonas