Stimulation of UvrD helicase by UvrAB.
Helicases play critical roles in all aspects of nucleic acid metabolism by catalyzing the remodeling of DNA and RNA structures. UvrD is an abundant helicase in Escherichia coli with well characterized functions in mismatch and nucleotide excision repair and a possible role in displacement of proteins such as RecA from single-stranded DNA. The mismatch repair protein MutL is known to stimulate UvrD. Here we show that the nucleotide excision repair proteins UvrA and UvrB can together stimulate UvrD-catalyzed unwinding of a range of DNA substrates containing strand discontinuities, including forked DNA substrates. The stimulation is specific for UvrD, as UvrAB failed to stimulate Rep helicase, a UvrD homologue. Moreover, although UvrAB can promote limited strand displacement, stimulation of UvrD did not require the strand displacement function of UvrAB. We conclude that UvrAB, like MutL, modulate UvrD helicase activity. This stimulation likely plays a role in DNA strand and protein displacement by UvrD in nucleotide excision repair. Promotion of UvrD-catalyzed unwinding of nicked duplexes by UvrAB may also explain the need for UvrAB and UvrD in Okazaki fragment processing in cells lacking DNA polymerase I. More generally, these data support the idea that helicase activity is regulated in vivo, with helicases acting as part of multisubunit complexes rather than in isolation.
Atkinson
John
J
School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, United Kingdom.
Guy
Colin P
CP
Cadman
Chris J
CJ
Moolenaar
Geri F
GF
Goosen
Nora
N
McGlynn
Peter
P
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D055162:Biocatalysis; D004247:DNA / Q000378:metabolism; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity
D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C058093:UvrB protein, E coli; D004247:DNA; C068631:UvrA protein, E coli; D000251:Adenosine Triphosphatases; C506746:UvrD protein, E coli; D004265:DNA Helicases