Journal : Journal of Bacteriology , vol. 182 , p. 2643–2648 , 2000
International Standard Numbers
Printed : 0021-9193
Electronic : 1098-5530
Publication type : Academic article
Issue : 9
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Several lactic acid bacteria produce so-called pediocin-like bacteriocins that share sequence characteristics, but
differ in activity and target cell specificity. The significance of a C-terminal disulfide bridge present in only a few of
these bacteriocins was studied by site-directed mutagenesis of pediocin PA-1 (which naturally contains the
bridge) and sakacin P (which lacks the bridge). Introduction of the C-terminal bridge into sakacin P broadened
the target cell specificity of this bacteriocin, as illustrated by the fact that the mutants were 10 to 20 times more
potent than the wild-type toward certain indicator strains, whereas the potency toward other indicator strains
remained essentially unchanged. Like pediocin PA-1, disulfide-containing sakacin P mutants had the same
potency at 20 and 37°C, whereas wild-type sakacin P was approximately 10 times less potent at 37°C than at
20°C. Reciprocal effects on target cell specificity and the temperature dependence of potency were observed
upon studying the effect of removing the C-terminal disulfide bridge from pediocin PA-1 by CysSer mutations.
These results clearly show that a C-terminal disulfide bridge in pediocin-like bacteriocins contributes to widening
of the antimicrobial spectrum as well as to higher potency at elevated temperatures. Interestingly, the differences
between sakacin P and pediocin PA-1 in terms of the temperature dependency of their activities correlated well
with the optimal temperatures for bacteriocin production and growth of the bacteriocin-producing strain.