Translesion Synthesis Past Platinum DNA Adducts by Human DNA Polymerase μ

• Published in: Biochemistry (Easton) 2003-02, Vol.42 (6), p.1777-1788
• Main Authors: Havener, Jody M, Nick McElhinny, Stephanie A, Bassett, Ekaterina, Gauger, Michele, Ramsden, Dale A, Chaney, Stephen G
• Format: Article
• Language: English
• Subjects: Catalysis; Cisplatin - chemistry; Cisplatin - toxicity; Deoxyadenine Nucleotides - chemistry; Deoxyguanine Nucleotides - chemistry; DNA Adducts - chemistry; DNA Damage; DNA Primers - chemistry; DNA, Single-Stranded - biosynthesis; DNA-Directed DNA Polymerase - chemistry; Guanine Nucleotides - chemistry; Humans; Oligonucleotides - chemistry; Organoplatinum Compounds - chemistry; Organoplatinum Compounds - toxicity; Templates, Genetic; Thymine Nucleotides - chemistry
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi0270079

DNA polymerase μ (pol μ) is a member of the pol X family of DNA polymerases, and it shares a number of characteristics of both DNA polymerase β (pol β) and terminal deoxynucleotidyl transferase (TdT). Because pol β has been shown to perform translesion DNA synthesis past cisplatin (CP)- and oxaliplatin (OX)-GG adducts, we determined the ability of pol μ to bypass these lesions. Pol μ bypassed CP and OX adducts with an efficiency of 14−35% compared to chain elongation on undamaged DNA, which is second only to pol η in terms of bypass efficiency. The relative ability of pol μ to bypass CP and OX adducts was dependent on both template structure and sequence context. Since pol μ has been shown to be more efficient on gapped DNA templates than on primed single-stranded DNA templates, we determined the ability of pol μ to bypass Pt-DNA adducts on both primed single-stranded and gapped templates. The bypass of Pt-DNA adducts by pol μ was highly error-prone on all templates, resulting in 2, 3, and 4 nt deletions. We postulate that bypass of Pt-DNA adducts by pol μ may involve looping out the Pt-GG adduct to allow chain elongation downstream of the adduct. This reaction appears to be facilitated by the presence of a downstream “acceptor” and a gap large enough to provide undamaged template DNA for elongation past the adduct, although gapped DNA is clearly not required for bypass.