Affiliation:
1. Biophysics Division, Indian Institute of Chemical Biology, Calcutta 700 032, India
Abstract
ABSTRACT
A new gene,
mutK
, of
Vibrio cholerae
, encoding a 19-kDa protein which is involved in repairing mismatches in DNA via a presumably methyl-independent pathway, has been identified. The product of the
mutK
gene cloned in either high- or low-copy-number vectors can reduce the spontaneous mutation frequency of
Escherichia coli mutS
,
mutL
,
mutU
, and
dam
mutants. The spontaneous mutation frequency of a chromosomal
mutK
knockout mutant was almost identical to that of wild-type
V. cholerae
cells, indicating that when the methyl-directed mismatch repair is blocked, the repair potential of MutK becomes apparent. The complete nucleotide sequence of the
mutK
gene has been determined, and the deduced amino acid sequence showed three open reading frames (ORFs), of which the ORF3 represents the
mutK
gene product. The
mutK
gene product has no significant homology with any of the proteins deposited in the EMBL data bank. ORF2, located upstream of
mutK
, encodes a 14-kDa protein which has more than 70% homology with a hypothetical protein found only downstream of the
E. coli vsr
gene. ORF1, located farther upstream of
mutK
, has more than 80% homology with a major cold shock protein found in several bacteria. Downstream of
mutK
, a partial ORF having 60% homology with an RNA methyltransferase has been identified. The
mutK
gene has recently been positioned in the ordered cloned DNA map of the genome of the
V. cholerae
strain from which the gene was isolated (10).
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
4 articles.
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