Affiliation:
1. Department of Food Science, University of Wisconsin—Madison, Madison, Wisconsin 53706
Abstract
ABSTRACT
A previously identified insert expressing an endopeptidase from a
Lactobacillus helveticus
CNRZ32 genomic library was characterized. Nucleotide sequence analysis revealed an open reading frame of 1,941 bp encoding a putative protein of 71.2 kDa which contained a zinc-protease motif. Protein homology searches revealed that this enzyme has 40% similarity with endopeptidase O (PepO) from
Lactococcus lactis
P8-2-47. Northern hybridization revealed that
pepO
is monocistronic and is expressed throughout the growth phase. CNRZ32 derivatives lacking PepO activity were constructed via gene replacement. Enzyme assays revealed that the PepO mutant had significantly reduced endopeptidase activity when compared to CNRZ32 with two of the three substrates examined. Growth studies indicated that PepO has no detectable effect on growth rate or acid production by
Lactobacillus helveticus
CNRZ32 in amino acid defined or skim milk medium.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
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