Structural Basis of Rev1-mediated Assembly of a Quaternary Vertebrate Translesion Polymerase Complex Consisting of Rev1, Heterodimeric Polymerase (Pol) κ, and Pol ζ

From the Department of Biochemistry, Duke University, Medical Center, Durham, North Carolina 27710.
Journal of Biological Chemistry (Impact Factor: 4.6). 08/2012; 287(40):33836-46. DOI: 10.1074/jbc.M112.394841
Source: PubMed

ABSTRACT DNA synthesis across lesions during genomic replication requires concerted actions of specialized DNA polymerases in a potentially mutagenic process known as translesion synthesis. Current models suggest that translesion synthesis in mammalian cells is achieved in two sequential steps, with a Y-family DNA polymerase (κ, η, ι, or Rev1) inserting a nucleotide opposite the lesion and with the heterodimeric B-family polymerase ζ, consisting of the catalytic Rev3 subunit and the accessory Rev7 subunit, replacing the insertion polymerase to carry out primer extension past the lesion. Effective translesion synthesis in vertebrates requires the scaffolding function of the C-terminal domain (CTD) of Rev1 that interacts with the Rev1-interacting region of polymerases κ, η, and ι and with the Rev7 subunit of polymerase ζ. We report the purification and structure determination of a quaternary translesion polymerase complex consisting of the Rev1 CTD, the heterodimeric Pol ζ complex, and the Pol κ Rev1-interacting region. Yeast two-hybrid assays were employed to identify important interface residues of the translesion polymerase complex. The structural elucidation of such a quaternary translesion polymerase complex encompassing both insertion and extension polymerases bridged by the Rev1 CTD provides the first molecular explanation of the essential scaffolding function of Rev1 and highlights the Rev1 CTD as a promising target for developing novel cancer therapeutics to suppress translesion synthesis. Our studies support the notion that vertebrate insertion and extension polymerases could structurally cooperate within a megatranslesion polymerase complex (translesionsome) nucleated by Rev1 to achieve efficient lesion bypass without incurring an additional switching mechanism.

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    • "The recruitment and recognition mechanisms between TLS polymerases and Rev1 revealed by our studies exactly agree with the functions of TLS polymerases in TLS. Remarkably, our fluorescence anisotropy studies show that the RIM of inserter polymerase k and extender polymerase z (Rev7/Rev3) can bind to the PID of Rev1 simultaneously (Supplementary Figure S5A and B), which is in accord with the parallel work published recently (Wojtaszek et al., 2012). Further confocal images of the HEK-293T cells prove that the triple complex of Rev1-PID/ Polk-RIM/Polz (Rev7/Rev3) can present even in cells (Figure 1H). "
    Journal of Molecular Cell Biology 12/2012; 5(3). DOI:10.1093/jmcb/mjs061 · 8.43 Impact Factor
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    ABSTRACT: In addition to DNA repair pathways, cells utilize translesion DNA synthesis (TLS) to bypass DNA lesions during replication. During TLS, Y-family DNA polymerase (Polη, Polκ, Polı and Rev1) inserts specific nucleotide opposite preferred DNA lesions, and then Polζ consisting of two subunits, Rev3 and Rev7, carries out primer extension. Here, we report the complex structures of Rev3-Rev7-Rev1(CTD) and Rev3-Rev7-Rev1(CTD)-Polκ(RIR). These two structures demonstrate that Rev1(CTD) contains separate binding sites for Polκ and Rev7. Our BIAcore experiments provide additional support for the notion that the interaction between Rev3 and Rev7 increases the affinity of Rev7 and Rev1. We also verified through FRET experiment that Rev1, Rev3, Rev7 and Polκ form a stable quaternary complex in vivo, thereby suggesting an efficient switching mechanism where the "inserter" polymerase can be immediately replaced by an "extender" polymerase within the same quaternary complex.
    Protein & Cell 11/2012; 3(11):864-74. DOI:10.1007/s13238-012-2102-x · 2.85 Impact Factor
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    ABSTRACT: Cancer cells display numerous abnormal characteristics which are initiated and maintained by elevated mutation rates and genome instability. Chromosomal DNA is continuously surveyed for the presence of damage or blocked replication forks by the DNA Damage Response (DDR) network. The DDR is complex and includes activation of cell cycle checkpoints, DNA repair, gene transcription, and induction of apoptosis. Duplicating a damaged genome is associated with elevated risks to fork collapse and genome instability. Therefore, the DNA Damage Tolerance (DDT) pathway is also employed to enhance survival and involves the recruitment of translesion DNA synthesis (TLS) polymerases to sites of replication fork blockade or single stranded DNA gaps left after the completion of replication in order to restore DNA to its double stranded form before mitosis. TLS polymerases are specialized for inserting nucleotides opposite DNA adducts, abasic sites, or DNA crosslinks. By definition, the DDT pathway is not involved in the actual repair of damaged DNA, but provides a mechanism to tolerate DNA lesions during replication thereby increasing survival and lessening the chance for genome instability. However this may be associated with increased mutagenesis. In this review, we will describe the specialized functions of Y family polymerases (Rev1, Polη, Polι and Polκ) and DNA polymerase ζ in lesion bypass, mutagenesis, and prevention of genome instability, the latter due to newly appreciated roles in DNA repair. The recently described role of the Fanconi anemia pathway in regulating Rev1 and Polζ-dependent TLS is also discussed in terms of their involvement in TLS, interstrand crosslink repair, and homologous recombination.
    Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 11/2012; DOI:10.1016/j.mrfmmm.2012.11.002 · 4.44 Impact Factor
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