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Appl. Environ. Microbiol., Oct 1995, 3573-3579, Vol 61, No. 10
MJ van Belkum and ME Stiles
Leucocin A is a small heat-stable bacteriocin produced by Leuconostoc
gelidum UAL187. A 2.9-kb fragment of plasmid DNA that contains the leucocin
structural gene and a second open reading frame (ORF) in an operon was
previously cloned (J. W. Hastings, M. Sailer, K. Johnson, K. L. Roy, J. C.
Vederas, and M. E. Stiles, J. Bacteriol. 173:7491-7500, 1991). When a 1-kb
DraI-HpaI fragment containing this operon was introduced into a
bacteriocin-negative variant (UAL187-13), immunity but no leucocin
production was detected. Leucocin production was observed when an 8-kb
SacI-HindIII fragment of the leucocin plasmid was introduced into L.
gelidum UAL187-13 and Lactococcus lactis IL1403. Nucleotide sequence
analysis of this 8-kb fragment revealed the presence of three ORFs in an
operon upstream of and on the strand opposite from the leucocin structural
gene. The first ORF (lcaE) encodes a putative protein of 149 amino acids
with no apparent function in leucocin A production. The second ORF (lcaC)
contains 717 codons that encode a protein homologous to members of the HlyB
family of ATP- binding cassette transporters. The third ORF (lcaD) contains
457 codons that encode a protein with marked similarity to LcnD, a protein
essential for the expression of the lactococcal bacteriocin lactococcin A.
Deletion mutations in lcaC and lcaD resulted in loss of leucocin
production, indicating that LcaC and LcaD are involved in production and
translocation of leucocin A. The secretion apparatus for lactococcin A did
not complement mutations in the lcaCD genes to express leucocin A in L.
lactis.(ABSTRACT TRUNCATED AT 250 WORDS)
Copyright © 1995, American Society for Microbiology
Molecular characterization of genes involved in the production of the bacteriocin leucocin A from Leuconostoc gelidum
Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Canada.
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