Bacteriocin 28b from Serratia marcescens N28b: identification of Escherichia coli surface components involved in bacteriocin binding and translocation.

Serratia marcescens N28b produces bacteriocin 28b, active against Escherichia coli. Bacteriocin sensitivity tests performed on a collection of E. coli envelope mutants, and isolation and characterization of E. coli bacteriocin-28b-insensitive mutants, showed that the core lipopolysaccharide, outer membrane proteins OmpA and OmpF, and TolQ, TolA, and TolB proteins are involved in bacteriocin 28b lethal activity. These mutants are assayed for bacteriocin 28b sensitivity under normal and bypass conditions, and their bacteriocin-binding ability was determined. The results obtained suggest that the core lipopolysaccaride and outer membrane proteins OmpA and OmpF are involved in bacteriocin 28b binding. Furthermore, bacteriocin 28b translocation requires proteins TolA, TolB, and TolQ.