Model for the regulation of CCR in <i>A</i>. <i>vinelandii</i>, in diauxic glucose-acetate growth.

A. The two-component system CbrA/CbrB is necessary for the expression of crcZ and crcY sRNAs genes from their RpoN-dependent promoters. A variant of CrcZ (CrcZ*) is produced from the processing of a cbrB-crcZ co-transcript, which is expressed from PcbrB. CrcZ, CrcZ* and CrcY sRNAs antagonize the translational repressing effect of Hfq-Crc on target genes. The phosphate groups at the 5’ end of crcY, crcZ and crcZ* transcripts are represented by yellow circles B. In the presence of both, acetate and glucose, translation of the gluP mRNA, encoding the glucose transporter, is inhibited by Hfq-Crc. C. This repression is alleviated as a consequence of the activation of the two-componente system CbrA/CbrB once the acetate is consumed, resulting in higher levels of CrcZ and CrcY, which sequester Hfq-Crc. For simplicity, other Hfq-Crc targets during glucose CCR are not shown [5]. Only three out of the six A-rich Hfq binding motifs of CrcZ/Y are represented to bind Hfq-Crc.