Affiliation:
1. Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309
Abstract
ABSTRACT
Sister chromatid exchange (SCE) in
Escherichia coli
results in the formation of circular dimer chromosomes, which are converted back to monomers by a compensating exchange at the
dif
resolvase site. Recombination at
dif
is site specific and can be monitored by utilizing a density label assay that we recently described. To characterize factors affecting SCE frequency, we analyzed dimer resolution at the
dif
site in a variety of genetic backgrounds and conditions. Recombination at
dif
was increased by known hyperrecombinogenic mutations such as
polA
,
dut
, and
uvrD
. It was also increased by a
fur
mutation, which increased oxidative DNA damage. Recombination at
dif
was eliminated by a
recA
mutation, reflecting the role of RecA in SCE and virtually all homologous recombination in
E. coli
. Interestingly, recombination at
dif
was reduced to approximately half of the wild-type levels by single mutations in either
recB
or
recF
, and it was virtually eliminated when both mutations were present. This result demonstrates the importance of both RecBCD and RecF to chromosomal recombination events in wild-type cells.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
88 articles.
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