title: How DNA polymerase X preferentially accommodates incoming dATP opposite 8-oxoguanine on the template.
abstract: The modified base 8-oxo-7,8-dihydro-2'-deoxyguanosine (oxoG) is a common DNA adduct produced by the oxidation of DNA by reactive oxygen species. Kinetic data reveal that DNA polymerase X (pol X) from the African swine fever virus incorporates adenine (dATP) opposite to oxoG with higher efficiency than the non-damaged G:C basepair. To help interpret the kinetic data, we perform molecular dynamics simulations of pol X/DNA complexes, in which the template base opposite to the incoming dNTP (dCTP, dATP, dGTP) is oxoG. Our results suggest that pol X accommodates the oxoGsyn:A mispair by sampling closed active conformations that mirror those observed in traditional Watson-Crick complexes. Moreover, for both the oxoGsyn:A and oxoG:C ternary complexes, conformational sampling of the polymerase follows previously described large subdomain movements, local residue motions, and active site reorganization. Interestingly, the oxoGsyn:A system exhibits superior active site geometry in comparison to the oxoG:C system. Simulations for the other mismatch basepair complexes reveal large protein subdomain movement for all systems, except for oxoG:G, which samples conformations close to the open state. In addition, active site geometry and basepairing of the template base with the incoming nucleotide, reveal distortions and misalignments that range from moderate (i.e., oxoG:Asyn) to extreme (i.e., oxoGanti/syn:G). These results agree with the available kinetic data for pol X and provide structural insights regarding the mechanism by which this polymerase can accommodate incoming nucleotides opposite oxoG. Our simulations also support the notion that α-helix E is involved both in DNA binding and active site stabilization. Our proposed mechanism by which pol X can preferentially accommodate dATP opposite template oxoG further underscores the role that enzyme dynamics and conformational sampling operate in polymerase fidelity and function.
authors: Department of Natural Sciences, Marymount Manhattan College, New York, New York. Electronic address: bsampoli@mmm.edu.
authors: Benedetta
authors: B
authors: Sampoli Benítez
authors: Zachary R
authors: ZR
authors: Barbati
authors: Karunesh
authors: K
authors: Arora
authors: Jasmina
authors: J
authors: Bogdanovic
authors: Tamar
authors: T
authors: Schlick
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry* / Q000378:metabolism; D003838:Deoxyadenine Nucleotides / Q000737:chemistry* / Q000378:metabolism; D006147:Guanine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D062105:Molecular Docking Simulation; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D011485:Protein Binding; D013379:Substrate Specificity
chemical_list: D003838:Deoxyadenine Nucleotides; C024829:8-hydroxyguanine; D006147:Guanine; D004247:DNA; C109534:DNA polymerase X; D004259:DNA-Directed DNA Polymerase