RESUMEN
In Pseudomonas aeruginosa the RNA chaperone Hfq and the catabolite repression control protein (Crc) act as post-transcriptional regulators during carbon catabolite repression (CCR). In this regard Crc is required for full-fledged Hfq-mediated translational repression of catabolic genes. RNAseq based transcriptome analyses revealed a significant overlap between the Crc and Hfq regulons, which in conjunction with genetic data supported a concerted action of both proteins. Biochemical and biophysical approaches further suggest that Crc and Hfq form an assembly in the presence of RNAs containing A-rich motifs, and that Crc interacts with both, Hfq and RNA. Through these interactions, Crc enhances the stability of Hfq/Crc/RNA complexes, which can explain its facilitating role in Hfq-mediated translational repression. Hence, these studies revealed for the first time insights into how an interacting protein can modulate Hfq function. Moreover, Crc is shown to interfere with binding of a regulatory RNA to Hfq, which bears implications for riboregulation. These results are discussed in terms of a working model, wherein Crc prioritizes the function of Hfq toward utilization of favored carbon sources.
Asunto(s)
Proteínas Bacterianas/genética , Represión Catabólica , Proteína de Factor 1 del Huésped/genética , Biosíntesis de Proteínas , Pseudomonas aeruginosa/genética , ARN Bacteriano/genética , Proteínas Represoras/genética , Proteínas Bacterianas/química , Proteínas Bacterianas/metabolismo , Sitios de Unión , Bordetella pertussis/genética , Bordetella pertussis/metabolismo , Metabolismo de los Hidratos de Carbono/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Regulación Bacteriana de la Expresión Génica , Proteína de Factor 1 del Huésped/química , Proteína de Factor 1 del Huésped/metabolismo , Cinética , Modelos Moleculares , Motivos de Nucleótidos , Unión Proteica , Dominios y Motivos de Interacción de Proteínas , Estructura Secundaria de Proteína , Pseudomonas aeruginosa/metabolismo , ARN Bacteriano/química , ARN Bacteriano/metabolismo , Regulón , Proteínas Represoras/química , Proteínas Represoras/metabolismo , TranscriptomaRESUMEN
The RNA chaperone Hfq regulates virulence and metabolism in the opportunistic pathogen Pseudomonas aeruginosa. During carbon catabolite repression (CCR) Hfq together with the catabolite repression control protein Crc can act as a translational repressor of catabolic genes. Upon relief of CCR, the level of the Hfq-titrating RNA CrcZ is increasing, which in turn abrogates Hfq-mediated translational repression. As the interdependence of Hfq-mediated and RNA based control mechanisms is poorly understood, we explored the possibility whether the regulatory RNA CrcZ can interfere with riboregulation. We first substantiate that the P. aeruginosa Hfq is proficient and required for riboregulation of the transcriptional activator gene antR by the small RNA PrrF1-2. Our studies further revealed that CrcZ can interfere with PrrF1-2/Hfq-mediated regulation of antR. The competition for Hfq can be rationalized by the higher affinity of Hfq for CrcZ than for antR mRNA.