Nucleic Acids Research, Vol 24, Issue 6 1099-1004, Copyright © 1996 by Oxford University Press
M Wakasugi, Y Abe, Y Yoshida, T Matsunaga and O Nikaido
UV damage-specific binding proteins are considered to play important roles
in early responses of cells irradiated with UV, including damage
recognition in the DNA repair process. We have surveyed nuclear and
cytoplasmic proteins which bind selectively to UV-irradiated DNA using an
electrophoretic mobility shift assay. We detected four distinct binding
activities with different mobilities in fractions separated from HeLa cells
by heparin chromatography. Three of them were found in nuclear extracts and
one in cytoplasmic extracts. We purified one of the binding factors from
nuclear extracts to homogeneity, which was designated NF-10 (the 10th
fraction of nuclear extract on heparin chromatography). It migrated as a 40
kDa polypeptide in SDS-PAGE, and bound to UV-irradiated double- stranded
DNA but not to unirradiated DNA. The binding pattern of the NF-10 protein
to DNA irradiated with UV corresponded to the induction kinetics of (6-4)
photoproduct. Removal of (6-4) photoproducts from UV- irradiated DNA by
(6-4) photoproduct- specific photolyase diminished the binding of NF-10
protein. These results suggest that the NF-10 protein binds to UV-damaged
DNA through (6-4) photoproduct. Immunoblot analysis using a monoclonal
antibody revealed that the NF-10 protein was expressed in cell lines from
all complementation groups of xeroderma pigmentosum, indicating that the
NF- 10 protein is a novel UV-damaged-DNA binding protein.
ARTICLES
Purification of a novel UV-damaged-DNA binding protein highly specific for (6-4) photoproduct
Division of Radiation Biology, Faculty of Pharmaceutical Sciences, Kanazawa University, Japan.
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