The prtR gene indirectly activates the bacteriocin production in P. fluorescens SF4c

FERNÁNDEZ, M; GODINO, A; PRINCIPE, A; FISCHER, S

Cordoba

Congreso; 52 Reunión Anual de SAIB; 2016

SAIB

Bacteriocins are proteins produced by bacteria that can kill closely related species. P. fluorescens SF4c is a plant-growth promoting bacterium that synthesizes bacteriocins (phage-like pyocins), which inhibit the growth of phytopathogenic strains belonging to the genera Pseudomonas and Xanthomonas. The complete pyocin cluster was identified in the genome of the strain SF4c, finding structural genes of R and F-type pyocins, as well as, regulatory and lytic genes. The gene prtR is one of these putative regulatory genes and its ortholog in P. aeruginosa encodes a repressor protein. The aim of this work was to study the function of prtR in strain SF4c. The amino acid sequence of PrtR from strain SF4c is characteristic of repressor proteins. PrtR has two Pfam domains: a helix-turn-helix DNA binding domain of transcription regulators in the N-terminal end and a peptidase-S24 domain with a C1 repressor in the C-terminal end. A mutant prtR was constructed by gene replacement via homologous recombination and called P. fluorescens SF4c-prtR. Surprisingly, this mutant showed a deficiency in bacteriocin production compared with the wild-type strain. These results indicate that prtR activates the pyocin production in strain SF4c, probably, by indirect modulation. PrtR could repress the activity of a second repressor, still unknown, leading to activation of pyocin synthesis as final result.