The CbrAB/Crc system controls the bacteriocin production in the PGPR Pseudomonas fluorescens SF39a

AGUSTINA GODINO; MARICRUZ FERNANDEZ; ANALÍA PRÍNCIPE; SONIA FISCHER

Mar del Plata

Congreso; LI reunión anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2015

P. fluorescens SF39a secretes a bacteriocin that inhibits the growth of phytopathogenic strains. The knowledge aboutthe regulation of this bacteriocin is relevant because this compound could be applied as biocontrol agents. The aim ofthis work was to study the role of the CbrAB/Crc system in the bacteriocin regulation in the strain SF39a. CbrAB/Crcpathway is composed by the CbrAB two component-system, the sRNA CrcZ and the protein Crc. Crc acts as atranslational repressor by binding to target mRNAs. When the CbrAB is activated, CbrB activates the transcription ofcrcZ and this sRNA counteracts Crc function by sequestration of the protein. In this study, mutants of SF39a in thecbrA, cbrB, crcZ and crc genes were obtained. CbrA, CbrB and CrcZ mutants showed an increase in bacteriocinproduction, while Crc mutant displayed a decrease in bacteriocin production with respect to the wild-type. Theseresults suggest that CbrAB/Crc pathway controls the bacteriocin production in strain SF39a. Probably, Crc couldrepress the translation of mRNAs encoding a repressor of the bacteriocin or directly activate bacteriocin genes.Moreover, the CbrA, CbrB, CrcZ and Crc mutants were less competitive than the wt strain in the wheat rhizosphere.In conclusion, the CbrAB/Crc system affects bacteriocin production and it is required for a successful establishmentof the bacteria in the environment.