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Appl. Environ. Microbiol., 07 1995, 2514-2520, Vol 61, No. 7
JP Coleman and LL Hudson
The gene encoding a conjugated bile acid hydrolase (CBAH) from Clostridium
perfringens 13 has been cloned and expressed in Escherichia coli, and its
nucleotide sequence has been determined. Nucleotide and predicted amino
acid sequence analyses indicated that the gene product is related to two
previously characterized amidases, a CBAH from Lactobacillus plantarum (40%
identity) and a penicillin V amidase from Bacillus sphaericus (34%
identity). The product is apparently unrelated to a CBAH from C.
perfringens for which N-terminal sequence information was determined. The
gene product was purified from recombinant E. coli and used to raise
antibody in rabbits. The presence of the protein in C. perfringens was then
confirmed by immunoblot analysis. The protein was shown to have a native
molecular weight of 147,000 and a subunit molecular weight of 36,100,
indicating its probable existence as a tetramer. Disruption of the
chromosomal C. perfringens CBAH gene with a chloramphenicol resistance
cartridge resulted in a mutant strain which retained partial CBAH activity.
Polyacrylamide gel electrophoresis followed by enzymatic activity staining
and immunoblotting indicated that the mutant strain no longer expressed the
cloned CBAH (CBAH-1) but did express at least one additional CBAH (CBAH-2).
CBAH-2 was immunologically distinct from CBAH-1, and its mobility on native
polyacrylamide gels was different from that of CBAH-1. Furthermore,
comparisons of pH optima and substrate specificities of CBAH activities
from recombinant E. coli and wild-type and mutant C. perfringens provided
further evidence for the presence of multiple CBAH activities in C.
perfringens.
Copyright © 1995, American Society for Microbiology
Cloning and characterization of a conjugated bile acid hydrolase gene from Clostridium perfringens
Department of Microbiology and Immunology, School of Medicine, East Carolina University, Greenville, North Carolina 27828-4354, USA.
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