Regulation of tailocins produced by Pseudomonas fluorescens SF4c

FERNANDEZ, M.; GODINO, A.; PRÍNCIPE, A.; LOPEZ RAMIREZ V.; MORALES, G.M; FISCHER, S.E.

Paraná

Congreso; 54 Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2018

Bacteriocins are antimicrobial proteins produced in bacteria to compete for nutrients and space. We previously reported that the synthesis of tailocins (phage-tail-like bacteriocins) in P. fluorescens SF4c is upregulated by mitomycin C, a SOS-response inducer. The aim of this work was to study the regulation of tailocins in P. fluorescens SF4c. Proteomics has been used as a tool to assist in understanding bacterial behavior upon exposure to different stimuli. In this report, a comparative proteomic analysis between bacteriocins extracted from cultures of strain SF4c treated with mitomycin C or left untreated was performed. When the cells were treated with mitomycin C, a greater abundance of bacteriocin-associated proteins was observed. Those findings confirmed the previous results. In P. aeruginosa, the bacteriocins expression is controlled by the PrtN activator and the PrtR repressor. Bacteriocin regulation, however, is unknown in P. fluorescens. An orthologue of prtR gene was identified in the tailocin cluster of strain SF4c, though no gene homologous to prtN was detected. Therefore, we constructed a prtR null-mutant. The production of tailocins was abolished in this mutant in both conditions (induced with mitomycin C or uninduced). Moreover, the tailocin expression was measured through the use of the transcriptional fusion to gfp. No expression was observed in the mutant whereas the strain SF4c displayed a significantly strong promoter activity. The promoter activity was partially restored in the complemented mutant. This suggested that, unlike in P. aeruginosa, PrtR regulates expression of bacteriocins in P. fluorescens in a positive fashion.