Repair of mitomycin C mono- and interstrand cross-linked DNA adducts by UvrABC: a new model.
Mitomycin C induces both MC-mono-dG and cross-linked dG-adducts in vivo. Interstrand cross-linked (ICL) dG-MC-dG-DNA adducts can prevent strand separation. In Escherichia coli cells, UvrABC repairs ICL lesions that cause DNA bending. The mechanisms and consequences of NER of ICL dG-MC-dG lesions that do not induce DNA bending remain unclear. Using DNA fragments containing a MC-mono-dG or an ICL dG-MC-dG adduct, we found (i) UvrABC incises only at the strand containing MC-mono-dG adducts; (ii) UvrABC makes three types of incisions on an ICL dG-MC-dG adduct: type 1, a single 5' incision on 1 strand and a 3' incision on the other; type 2, dual incisions on 1 strand and a single incision on the other; and type 3, dual incisions on both strands; and (iii) the cutting kinetics of type 3 is significantly faster than type 1 and type 2, and all of 3 types of cutting result in producing DSB. We found that UvrA, UvrA+UvrB and UvrA+UvrB+UvrC bind to MC-modified DNA specifically, and we did not detect any UvrB- and UvrB+UvrC-DNA complexes. Our findings challenge the current UvrABC incision model. We propose that DSBs resulted from NER of ICL dG-MC-dG adducts contribute to MC antitumor activity and mutations.
Weng
Mao-wen
MW
Department of Environmental Medicine, Pathology, and Medicine, New York University School of Medicine, Tuxedo, New York 10987, USA.
Zheng
Yi
Y
Jasti
Vijay P
VP
Champeil
Elise
E
Tomasz
Maria
M
Wang
Yinsheng
Y
Basu
Ashis K
AK
Tang
Moon-shong
MS
D018736:DNA Adducts / Q000737:chemistry / Q000378:metabolism*; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D004706:Endodeoxyribonucleases / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D016685:Mitomycin / Q000737:chemistry / Q000378:metabolism*; D008957:Models, Genetic
D018736:DNA Adducts; D029968:Escherichia coli Proteins; C056417:mitomycin C-DNA adduct; D016685:Mitomycin; D004706:Endodeoxyribonucleases; C036385:endodeoxyribonuclease uvrABC