Affiliation:
1. Molecular and Cellular Biology Graduate Program, Morrill Science Center, University of Massachusetts at Amherst, Amherst, Massachusetts 01003
2. Department of Microbiology, Morrill Science Center IV N203, University of Massachusetts at Amherst, Amherst, Massachusetts 01003
Abstract
ABSTRACT
RecA is important for recombination, DNA repair, and SOS induction. In
Escherichia coli
, RecBCD, RecFOR, and RecJQ prepare DNA substrates onto which RecA binds. UvrD is a 3′-to-5′ helicase that participates in methyl-directed mismatch repair and nucleotide excision repair.
uvrD
deletion mutants are sensitive to UV irradiation, hypermutable, and hyper-rec. In vitro, UvrD can dissociate RecA from single-stranded DNA. Other experiments suggest that UvrD removes RecA from DNA where it promotes unproductive reactions. To test if UvrD limits the number and/or the size of RecA-DNA structures in vivo, an
uvrD
mutation was combined with
recA-gfp
. This
recA
allele allows the number of RecA structures and the amount of RecA at these structures to be assayed in living cells.
uvrD
mutants show a threefold increase in the number of RecA-GFP foci, and these foci are, on average, nearly twofold higher in relative intensity. The increased number of RecA-green fluorescent protein foci in the
uvrD
mutant is dependent on
recF
,
recO
,
recR
,
recJ
, and
recQ
. The increase in average relative intensity is dependent on
recO
and
recQ
. These data support an in vivo role for UvrD in removing RecA from the DNA.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
41 articles.
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