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J. Bacteriol., 03 1995, 1144-1151, Vol 177, No. 5
LE Quadri, M Sailer, MR Terebiznik, KL Roy, JC Vederas and ME Stiles
Cloning of a 16-kb DNA fragment from the 61-kb plasmid of Carnobacterium
piscicola LV17B into plasmidless C. piscicola LV17C restores the production
of the plasmid-encoded carnobacteriocin B2 and the chromosomally-encoded
carnobacteriocin BM1 and restores the immune phenotype. This fragment also
has sufficient genetic information to allow the expression of
carnobacteriocin B2 and its immunity in a heterologous host. The gene locus
(cbiB2) responsible for immunity to carnobacteriocin B2 is located
downstream of the structural gene for carnobacteriocin B2 and encodes a
protein of 111 amino acids (CbiB2). CbiB2 was expressed in Escherichia coli
as a fusion of the maltose- binding protein and CbiB2. The fusion protein
was purified on an amylose column and cleaved with factor Xa, and pure
CbiB2 was isolated by high-performance liquid chromatography. The
N-terminal amino acid sequence and mass spectrometry (molecular weight
[mean +/- standard error], 12,662.2 +/- 3.4) of the purified protein agree
with the information deduced from the nucleotide sequence of cbiB2. Western
blot (immunoblot) analysis indicates that the majority of the intracellular
pool of this immunity protein is in the cytoplasm and that a smaller
proportion is associated with the membrane. CbiB2 confers immunity to
carnobacteriocin B2, but not to carnobacteriocin BM1, when it is expressed
in homologous or heterologous hosts. No protective effect is observed for
sensitive cells growing in the presence of the bacteriocin when the
immunity protein is added to the medium. The purified immunity protein does
not show significant binding to microtiter plates coated with
carnobacteriocin B2 and is not able to inactivate the bacteriocin in
solution.
Copyright © 1995, American Society for Microbiology
Characterization of the protein conferring immunity to the antimicrobial peptide carnobacteriocin B2 and expression of carnobacteriocins B2 and BM1
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Canada.
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