title: Effect of Crc and Hfq proteins on the transcription, processing, and stability of the Pseudomonas putida CrcZ sRNA.
abstract: In Pseudomonas putida, the Hfq and Crc proteins regulate the expression of many genes in response to nutritional and environmental cues, by binding to mRNAs that bear specific target motifs and inhibiting their translation. The effect of these two proteins is antagonized by the CrcZ and CrcY small RNAs (sRNAs), the levels of which vary greatly according to growth conditions. The crcZ and crcY genes are transcribed from promoters PcrcZ and PcrcY, respectively, a process that relies on the CbrB transcriptional activator and the RpoN σ factor. Here we show that crcZ can also be transcribed from the promoter of the immediate upstream gene, cbrB, a weak constitutive promoter. The cbrB-crcZ transcript was processed to render a sRNA very similar in size to the CrcZ produced from promoter PcrcZ The processed sRNA, termed CrcZ*, was able to antagonize Hfq/Crc because, when provided in trans, it relieved the deregulated Hfq/Crc-dependent hyperrepressing phenotype of a ΔcrcZΔcrcY strain. CrcZ* may help in attaining basal levels of CrcZ/CrcZ* that are sufficient to protect the cell from an excessive Hfq/Crc-dependent repression. Since a functional sRNA can be produced from PcrcZ, an inducible strong promoter, or by cleavage of the cbrB-crcZ mRNA, crcZ can be considered a 3'-untranslated region of the cbrB-crcZ mRNA. In the absence of Hfq, the processed form of CrcZ was not observed. In addition, we show that Crc and Hfq increase CrcZ stability, which supports the idea that these proteins can form a complex with CrcZ and protect it from degradation by RNases.
authors: Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Cantoblanco, 28049 Madrid, Spain.
authors: Sofía
authors: S
authors: Hernández-Arranz
authors: Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Cantoblanco, 28049 Madrid, Spain.
authors: Dione
authors: D
authors: Sánchez-Hevia
authors: Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Cantoblanco, 28049 Madrid, Spain.
authors: Fernando
authors: F
authors: Rojo
authors: Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Cantoblanco, 28049 Madrid, Spain.
authors: Renata
authors: R
authors: Moreno
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D011401:Promoter Regions, Genetic; D016958:Pseudomonas putida / Q000235:genetics*; D012323:RNA Processing, Post-Transcriptional; D012329:RNA, Bacterial / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger
keywords: RNA processing; bacteria; catabolite repression; global regulation of gene expression; small RNAs