CrcZ and CrcX regulate carbon source utilization in Pseudomonas syringaepathovar tomatostrain DC3000

Small non-coding RNAs (ncRNAs) are important components of many regulatory pathways in bacteria and play key roles in regulating factors important for virulence. Carbon catabolite repression control is modulated by small RNAs (crcZor crcZand crcY) in Pseudomonas aeruginosaand Pseudomonas putida. In this study, we demonstrate that expression of crcZand crcX(formerly designated psr1and psr2, respectively) is dependent upon RpoN together with the two-component system CbrAB, and is influenced by the carbon source present in the medium in the model plant pathogen Pseudomonas syringaepv tomatoDC3000. The distribution of the members of the Crc ncRNA family was also determined by screening available genomic sequences of the Pseudomonads. Interestingly, variable numbers of the Crc family members exist in Pseudomonas genomes. The ncRNAs are comprised of three main subfamilies, named CrcZ, CrcX and CrcY. Most importantly the CrcX subfamily appears to be unique to all P. syringaestrains sequenced to date.