Affiliation:
1. Departments of Microbiology & Molecular Genetics and Medicine, University of California Irvine, Irvine, California 92697-4025
Abstract
ABSTRACT
After unsuccessful attempts to recover a viable RecA-deficient mutant of the Lyme borreliosis agent
Borrelia burgdorferi
, we characterized the functional activities of RecA of
B. burgdorferi
, as well as RecA of the relapsing fever spirochete
Borrelia hermsii
and the free-living spirochete
Leptospira biflexa
, in a
recA
mutant of
Escherichia coli
. As a control,
E. coli
RecA was expressed from the same plasmid vector. DNA damage repair activity was assessed after exposure of the transgenic cells to UV light or the radiomimetic chemicals methyl methanesulfonate and mitomycin C. Recombination activity in the cells was assessed by using an assay for homologous recombination between repeats in the chromosome and by measuring the ability of the cells to foster lytic growth by
red gam
mutant bacteriophage λ. Overall, we found that transgenic cells with
recA
genes of
B. burgdorferi
,
B. hermsii
, and
L. biflexa
had approximately equivalent activities in promoting homologous recombination in the
lacZ
duplication assay, but cells with
B. burgdorferi recA
and, most notably,
B. hermsii recA
were significantly less capable than cells with
L. biflexa recA
or
E. coli recA
in responding to DNA damage or in facilitating plaque formation in the phage assay. The comparatively poor function of
Borrelia recA
in the latter set of assays may be the consequence of impaired coordination in the loading of the transgenic RecA by RecBCD and/or RecFOR in
E. coli
.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
15 articles.
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