Regulation of tailocins produced by Pseudomonas fluorescens SF4c

FERNÁNDEZ, M; GODINO, A; PRINCIPE, A; LOPEZ RAMIREZ, V; MORALES, G; FISCHER, S

Parana, Entre Rios

Congreso; 54th Reunión Anual de SAIB; 2018

SAIB

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