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DNA analysis of the genes encoding acidocin LF221 A and acidocin LF221 B, two bacteriocins produced by Lactobacillus gasseri LF221

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Author: Majhenič, A.Č. · Venema, K. · Allison, G.E. · Matijašić, B.B. · Rogelj, I. · Klaenhammer, T.R.
Type:article
Date:2004
Institution: TNO Voeding
Source:Applied Microbiology and Biotechnology, 6, 63, 705-714
Identifier: 237594
doi: doi:10.1007/s00253-003-1424-2
Keywords: Health · Physiological Sciences · acidocin lf221 a · acidocin lf221 b · amino acid · bacteriocin · brochocin b · food preservative · gassericin x · lactacin f · lactococcin n · probiotic agent · thermophilin b · unclassified drug · bacterium · amino terminal sequence · article · bacterial gene · bacterial strain · controlled study · DNA determination · DNA sequence · genetic code · Lactobacillus gasseri · molecular cloning · nonhuman · nucleotide sequence · open reading frame · polymerase chain reaction · sequence analysis · sequence homology · Southern blotting · structural gene · Amino Acid Sequence · Bacteriocins · Base Sequence · Cloning, Molecular · Codon, Initiator · Codon, Terminator · DNA, Bacterial · Genes, Bacterial · Lactobacillus · Molecular Sequence Data · Open Reading Frames · Plasmids · Probiotics · Promoter Regions (Genetics) · Protein Sorting Signals · Sequence Analysis, DNA · Sequence Homology · Animalia · Bacteria (microorganisms) · Lactobacillus · Lactobacillus gasseri · Negibacteria

Abstract

Lactobacillus gasseri LF221, an isolate from the feces of a child, produces two bacteriocins. Standard procedures for molecular techniques were used to locate, clone and sequence the fragments of LF221 chromosomal DNA carrying the acidocin LF221 A and B structural genes, respectively. Sequencing analysis revealed the gene of acidocin LF221 A to be an open reading frame encoding a protein composed of 69 amino acids, including a 16-amino-acid N-terminal extension. The acidocin LF221 B gene was found to encode a 65-amino-acid bacteriocin precursor with a 17-amino-acid N-terminal leader peptide. DNA homology searches showed similarities of acidocin LF221 A to brochocin B, lactococcin N and thermophilin B, whereas acidocin LF221 B exhibited some homology to lactacin F and was virtually identical to gassericin X. The peptides encoded by orfA1 and orfB3 showed characteristics of class II bacteriocins and are suspected to be the complementary peptides of acidocin A and B, respectively. orfA3 and orfB5 are proposed to encode putative immunity proteins for the acidocins. Acidocin LF221 A and acidocin LF221 B are predicted to be members of the two-component class II bacteriocins, where acidocin LF221 A appears to be a novel bacteriocin. L. gasseri LF221 is being developed as a potential probiotic strain and a food/feed preservative. Detailed characterization of its acidocins is an important piece of background information useful in applying the strain into human or animal consumption. The genetic information on both acidocins also enables tracking of the LF221 strain in mixed populations and complex environments.