The relationships between XPC binding to conformationally diverse DNA adducts and their excision by the human NER system: is there a correlation?
The first eukaryotic NER factor that recognizes NER substrates is the heterodimeric XPC-RAD23B protein. The currently accepted hypothesis is that this protein recognizes the distortions/destabilization caused by DNA lesions rather than the lesions themselves. The resulting XPC-RAD23B-DNA complexes serve as scaffolds for the recruitment of subsequent NER factors that lead to the excision of the oligonucleotide sequences containing the lesions. Based on several well-known examples of DNA lesions like the UV radiation-induced CPD and 6-4 photodimers, as well as cisplatin-derived intrastrand cross-linked lesions, it is generally believed that the differences in excision activities in human cell extracts is correlated with the binding affinities of XPC-RAD23B to these DNA lesions. However, using electrophoretic mobility shift assays, we have found that XPC-RAD23B binding affinities of certain bulky lesions derived from metabolically activated polycyclic aromatic hydrocarbon compounds such as benzo[a]pyrene and dibenzo[a,l]pyrene, are not directly, or necessarily correlated with NER excision activities observed in cell-free extracts. These findings point to features of XPC-RAD23B-bulky DNA adduct complexes that may involve the formation of NER-productive or unproductive forms of binding that depend on the structural and stereochemical properties of the DNA adducts studied. The pronounced differences in NER cleavage efficiencies observed in cell-free extracts may be due to differences in the successful recruitment of subsequent NER factors by the XPC-RAD23B-DNA adduct complexes, and/or in the verification step. These phenomena appear to depend on the structural and conformational properties of the class of bulky DNA adducts studied.
Chemistry Department, New York University, Silver Complex, 100 Washington Square East, New York, NY 10012, USA.
Yuan-Cho
YC
Lee
Biology Department, New York University, Silver Complex, 100 Washington Square East, New York, NY 10012, USA.
Yuqin
Y
Cai
Biology Department, New York University, Silver Complex, 100 Washington Square East, New York, NY 10012, USA.
Hong
H
Mu
Biology Department, New York University, Silver Complex, 100 Washington Square East, New York, NY 10012, USA.
Suse
S
Broyde
Department of Pharmacology, Penn State College of Medicine, Hershey, PA 17033, USA.
Shantu
S
Amin
Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA.
Xuejing
X
Chen
Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA.
Jung-Hyun
JH
Min
Chemistry Department, New York University, Silver Complex, 100 Washington Square East, New York, NY 10012, USA. Electronic address: ng1@nyu.edu.
Nicholas E
NE
Geacintov
D001580:Benzopyrenes / Q000494:pharmacology; D002945:Cisplatin / Q000494:pharmacology; D018736:DNA Adducts / Q000096:biosynthesis / Q000235:genetics*; D004249:DNA Damage / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D004260:DNA Repair / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D045643:DNA Repair Enzymes / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D006801:Humans; D009690:Nucleic Acid Conformation / Q000187:drug effects / Q000528:radiation effects; D011485:Protein Binding; D011487:Protein Conformation / Q000187:drug effects / Q000528:radiation effects; D014466:Ultraviolet Rays
D001580:Benzopyrenes; D018736:DNA Adducts; D004268:DNA-Binding Proteins; C513287:RAD23B protein, human; C086984:XPC protein, human; D045643:DNA Repair Enzymes; D002945:Cisplatin
Benzo[a]pyrene; DNA adduct; Dibenzo[a,l]pyrene; Electrophoretic mobility shift assay; Nucleotide excision repair (NER); XPC-RAD23B binding