Benzene-derived N2-(4-hydroxyphenyl)-deoxyguanosine adduct: UvrABC incision and its conformation in DNA

Journal Article · Mon Jun 14 00:00:00 EDT 2010 · Toxicology Letters

OSTI ID:986494

Hang, Bo; Rodriguez, Ben; Yang, Yanu; Guliaev, Anton B; Chenna, Ahmed

Benzene, a ubiquitous human carcinogen, forms DNA adducts through its metabolites such as p-benzoquinone (p-BQ) and hydroquinone (HQ). N(2)-(4-Hydroxyphenyl)-2'-deoxyguanosine (N(2)-4-HOPh-dG) is the principal adduct identified in vivo by (32)P-postlabeling in cells or animals treated with p-BQ or HQ. To study its effect on repair specificity and replication fidelity, we recently synthesized defined oligonucleotides containing a site-specific adduct using phosphoramidite chemistry. We here report the repair of this adduct by Escherichia coli UvrABC complex, which performs the initial damage recognition and incision steps in the nucleotide excision repair (NER) pathway. We first showed that the p-BQ-treated plasmid was efficiently cleaved by the complex, indicating the formation of DNA lesions that are substrates for NER. Using a 40-mer substrate, we found that UvrABC incises the DNA strand containing N(2)-4-HOPh-dG in a dose- and time-dependent manner. The specificity of such repair was also compared with that of DNA glycosylases and damage-specific endonucleases of E. coli, both of which were found to have no detectable activity toward N(2)-4-HOPh-dG. To understand why this adduct is specifically recognized and processed by UvrABC, molecular modeling studies were performed. Analysis of molecular dynamics trajectories showed that stable G:C-like hydrogen bonding patterns of all three Watson-Crick hydrogen bonds are present within the N(2)-4-HOPh-G:C base pair, with the hydroxyphenyl ring at an almost planar position. In addition, N(2)-4-HOPh-dG has a tendency to form more stable stacking interactions than a normal G in B-type DNA. These conformational properties may be critical in differential recognition of this adduct by specific repair enzymes.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: Life Sciences Division
• DOE Contract Number: DE-AC02-05CH11231; CA72079
• OSTI ID: 986494
• Report Number(s): LBNL-3840E; TRN: US201017%%364
• Journal Information: Toxicology Letters, Journal Name: Toxicology Letters
• Country of Publication: United States
• Language: English

Related Subjects

59
ADDUCTS
ANIMALS
BENZENE
BONDING
CHEMISTRY
DNA
DNA ADDUCTS
ENDONUCLEASES
ENZYMES
ESCHERICHIA COLI
EXCISION REPAIR
HYDROGEN
IN VIVO
METABOLITES
NUCLEOTIDES
OLIGONUCLEOTIDES
PLASMIDS
REPAIR
SPECIFICITY
SUBSTRATES
TRAJECTORIES
enzene
Hydroquinone
p-Benzoquinone
DNA adduct
UvrABC
Nucleotide excision repair
Adduct conformation
Molecular modeling