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Appl. Environ. Microbiol., 03 1995, 1061-1067, Vol 61, No. 3
K Kanatani, M Oshimura and K Sano
Acidocin A, a bacteriocin produced by Lactobacillus acidophilus TK9201, is
active against closely related lactic acid bacteria and food-borne
pathogens including Listeria monocytogenes. The bacteriocin was purified to
homogeneity by ammonium sulfate precipitation and sequential ion-exchange
and reversed-phase chromatographies. The molecular mass was determined by
high-performance liquid chromatography gel filtration to be 6,500 Da. The
sequence of the first 16 amino acids of the N terminus was determined, and
oligonucleotide probes based on this sequence were constructed to detect
the acidocin A structural gene acdA. The probes hybridized to the 4.5-kb
EcoRI fragment of a 45-kb plasmid, pLA9201, present in L. acidophilus
TK9201, and the hybridizing region was further localized to the 0.9-kb
KpnI-XbaI fragment. Analysis of the nucleotide sequence of this fragment
revealed that acidocin A was synthesized as an 81-amino-acid precursor
including a 23-amino-acid N-terminal extension. An additional open reading
frame (ORF2) encoding a 55-amino-acid polypeptide was found downstream of
and in the same operon as acdA. Transformants containing this ORF2 became
resistant to acidocin A, suggesting that ORF2 encodes an immunity function
for acidocin A. The 7.2-kb SacI-XbaI fragment containing the upstream
region of acdA of pLA9201 was necessary for acidocin A expression in the
acidocin A-deficient mutant, L. acidophilus TK9201-1, and other
Lactobacillus strains.
Copyright © 1995, American Society for Microbiology
Isolation and characterization of acidocin A and cloning of the bacteriocin gene from Lactobacillus acidophilus
Research Laboratory, Tamon Sake Brewing Co., Ltd., Hyogo, Japan.
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