Sakacin P is a small, heat-stable, ribosomally synthesized peptide produced by certain strains of It inhibits the growth of several Gram-positive bacteria, including A 7.6 kb chromosomal DNA fragment from Lb674 encompassing all genes responsible for sakacin P production and immunity was sequenced and introduced into strains Lb790 and Lb706X which are bacteriocin-negative and sensitive to sakacin P. The transformants produced sakacin P in comparable amounts to the parental strain, Lb674. The sakacin P gene cluster comprised six consecutive genes: and all transcribed in the same direction. The deduced proteins SppK and SppR resembled the histidine kinase and response regulator proteins of bacterial two-component signal transducing systems of the AgrB/AgrA-type. The genes and encoded the sakacin P preprotein and the putative immunity protein, respectively. The predicted proteins SppT and SppE showed strong similarities to the proposed transport proteins of several other bacteriocins and to proteins implicated in the signal-sequence-independent export of haemolysin A. Deletion and frameshift mutation analyses showed that and were essential for sakacin P production in Lb706X. The putative SpiA peptide was shown to be involved in immunity to sakacin P. Analogues of and were found on the chromosomes of Lb706X and Lb790, indicating the presence of an incomplete gene cluster in these strains.


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