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Human RAD52 Captures and Holds DNA Strands, Increases DNA Flexibility, and
Prevents Melting of Duplex DNA: Implications for DNA Recombination
#MMPMID28329678
Brouwer I
; Zhang H
; Candelli A
; Normanno D
; Peterman EJG
; Wuite GJL
; Modesti M
Cell Rep
2017[Mar]; 18
(12
): 2845-2853
PMID28329678
show ga
Human RAD52 promotes annealing of complementary single-stranded DNA (ssDNA).
In-depth knowledge of RAD52-DNA interaction is required to understand how its
activity is integrated in DNA repair processes. Here, we visualize individual
fluorescent RAD52 complexes interacting with single DNA molecules. The
interaction with ssDNA is rapid, static, and tight, where ssDNA appears to wrap
around RAD52 complexes that promote intra-molecular bridging. With
double-stranded DNA (dsDNA), interaction is slower, weaker, and often diffusive.
Interestingly, force spectroscopy experiments show that RAD52 alters the
mechanics dsDNA by enhancing DNA flexibility and increasing DNA contour length,
suggesting intercalation. RAD52 binding changes the nature of the overstretching
transition of dsDNA and prevents DNA melting, which is advantageous for strand
clamping during or after annealing. DNA-bound RAD52 is efficient at capturing
ssDNA in trans. Together, these effects may help key steps in DNA repair, such as
second-end capture during homologous recombination or strand annealing during
RAD51-independent recombination reactions.
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