title: Mechanism of error-free DNA synthesis across N1-methyl-deoxyadenosine by human DNA polymerase-ι.
abstract: N1-methyl-deoxyadenosine (1-MeA) is formed by methylation of deoxyadenosine at the N1 atom. 1-MeA presents a block to replicative DNA polymerases due to its inability to participate in Watson-Crick (W-C) base pairing. Here we determine how human DNA polymerase-ι (Polι) promotes error-free replication across 1-MeA. Steady state kinetic analyses indicate that Polι is ~100 fold more efficient in incorporating the correct nucleotide T versus the incorrect nucleotide C opposite 1-MeA. To understand the basis of this selectivity, we determined ternary structures of Polι bound to template 1-MeA and incoming dTTP or dCTP. In both structures, template 1-MeA rotates to the syn conformation but pairs differently with dTTP versus dCTP. Thus, whereas dTTP partakes in stable Hoogsteen base pairing with 1-MeA, dCTP fails to gain a "foothold" and is largely disordered. Together, our kinetic and structural studies show how Polι maintains discrimination between correct and incorrect incoming nucleotide opposite 1-MeA in preserving genome integrity.
authors.affiliation: Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, Box 1677, 1425 Madison Avenue, New York, NY 10029, USA.
authors.forename: Rinku
authors.initials: R
authors.lastname: Jain
authors.affiliation: Department of Biochemistry and Molecular Biology, 301 University Blvd., University of Texas Medical Branch, Galveston, TX 77755-1061, USA.
authors.forename: Jayati Roy
authors.initials: JR
authors.lastname: Choudhury
authors.affiliation: Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, Box 1677, 1425 Madison Avenue, New York, NY 10029, USA.
authors.forename: Angeliki
authors.initials: A
authors.lastname: Buku
authors.affiliation: Department of Biochemistry and Molecular Biology, 301 University Blvd., University of Texas Medical Branch, Galveston, TX 77755-1061, USA.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Johnson
authors.affiliation: Department of Biochemistry and Molecular Biology, 301 University Blvd., University of Texas Medical Branch, Galveston, TX 77755-1061, USA.
authors.forename: Louise
authors.initials: L
authors.lastname: Prakash
authors.affiliation: Department of Biochemistry and Molecular Biology, 301 University Blvd., University of Texas Medical Branch, Galveston, TX 77755-1061, USA.
authors.forename: Satya
authors.initials: S
authors.lastname: Prakash
authors.affiliation: Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, Box 1677, 1425 Madison Avenue, New York, NY 10029, USA.
authors.forename: Aneel K
authors.initials: AK
authors.lastname: Aggarwal
mesh_terms: D020029:Base Pairing; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D004247:DNA / Q000096:biosynthesis* / Q000737:chemistry; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry / Q000378:metabolism*; D003839:Deoxyadenosines / Q000737:chemistry / Q000378:metabolism*; D003845:Deoxycytosine Nucleotides / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D020836:Protein Structure, Quaternary; D013942:Thymine Nucleotides / Q000737:chemistry / Q000378:metabolism; D000094769:DNA Polymerase iota
chemical_list: D003839:Deoxyadenosines; D003845:Deoxycytosine Nucleotides; D013942:Thymine Nucleotides; C024107:2'-deoxycytidine 5'-triphosphate; D004247:DNA; D004259:DNA-Directed DNA Polymerase; C024157:thymidine 5'-triphosphate; D000094769:DNA Polymerase iota; C000722070:POLI protein, human