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Appl. Environ. Microbiol., 09 1996, 3313-3318, Vol 62, No. 9
G Fimland, OR Blingsmo, K Sletten, G Jung, IF Nes and J Nissen-Meyer
The pediocin-like bacteriocins, produced by lactic acid bacteria, are
bactericidal polypeptides with very similar primary structures. Peptide
synthesis followed by reverse-phase and ion-exchange chromatographies
yielded biologically active pediocin-like bacteriocins in amounts and with
a purity sufficient for characterizing their structure and mode of action.
Despite similar primary structures, the pediocin-like bacteriocins, i.e.,
pediocin PA-1, sakacin P, curvacin A, and leucocin A, differed in their
relative toxicities against various bacterial strains. On the basis of the
primary structures, the polypeptides of these bacteriocins were divided
into two modules: the relatively hydrophilic and well conserved N-terminal
region, and the somewhat more diverse and hydrophobic C-terminal region. By
peptide synthesis, four new biologically active hybrid bacteriocins were
constructed by interchanging corresponding modules from various
pediocin-like bacteriocins. All of the new hybrid bacteriocin constructs
had bactericidal activity. The relative sensitivity of different bacterial
strains to a hybrid bacteriocin was similar to that to the bacteriocin from
which the C-terminal module was derived and quite different from that to
the bacteriocin from which the N-terminal was derived. Thus, the C-terminal
part of the pediocin-like bacteriocins is an important determinant of the
target cell specificity. The synthetic bacteriocins were more stable than
natural isolates, presumably as a result of the absence of contaminating
proteases. However, some of the synthetic bacteriocins lost activity, but
this was detectable only after months of storage. Mass spectrometry
suggested that this instability was due to oxidation of methionine
residues, resulting in a 10- to 100-fold reduction in activity.
Copyright © 1996, American Society for Microbiology
New biologically active hybrid bacteriocins constructed by combining regions from various pediocin-like bacteriocins: the C-terminal region is important for determining specificity
Department of Biochemistry, University of Oslo, Norway.
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