3gv8
Human DNA polymerase iota in complex with T template DNA and incoming dGTPHuman DNA polymerase iota in complex with T template DNA and incoming dGTP
Structural highlights
Function[POLI_HUMAN] Error-prone DNA polymerase specifically involved in DNA repair. Plays an important role in translesion synthesis, where the normal high-fidelity DNA polymerases cannot proceed and DNA synthesis stalls. Favors Hoogsteen base-pairing in the active site. Inserts the correct base with high-fidelity opposite an adenosine template. Exhibits low fidelity and efficiency opposite a thymidine template, where it will preferentially insert guanosine. May play a role in hypermutation of immunogobulin genes. Forms a Schiff base with 5'-deoxyribose phosphate at abasic sites, but may not have lyase activity.[1] [2] [3] [4] [5] [6] [7] Evolutionary Conservation![]() Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedHuman DNA polymerase iota (pol iota) is a unique member of Y-family polymerases, which preferentially misincorporates nucleotides opposite thymines (T) and halts replication at T bases. The structural basis of the high error rates remains elusive. We present three crystal structures of pol complexed with DNA containing a thymine base, paired with correct or incorrect incoming nucleotides. A narrowed active site supports a pyrimidine to pyrimidine mismatch and excludes Watson-Crick base pairing by pol. The template thymine remains in an anti conformation irrespective of incoming nucleotides. Incoming ddATP adopts a syn conformation with reduced base stacking, whereas incorrect dGTP and dTTP maintain anti conformations with normal base stacking. Further stabilization of dGTP by H-bonding with Gln59 of the finger domain explains the preferential T to G mismatch. A template 'U-turn' is stabilized by pol and the methyl group of the thymine template, revealing the structural basis of T stalling. Our structural and domain-swapping experiments indicate that the finger domain is responsible for pol's high error rates on pyrimidines and determines the incorporation specificity. Structural basis of error-prone replication and stalling at a thymine base by human DNA polymerase iota.,Kirouac KN, Ling H EMBO J. 2009 Jun 3;28(11):1644-54. PMID:19440206[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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OCA- DNA-directed DNA polymerase
- Human
- Kirouac, K N
- Ling, H
- Dna damage
- Dna repair
- Dna replication
- Dna synthesis
- Dna-binding
- Dna-directed dna polymerase
- Error prone replication
- Magnesium
- Metal-binding
- Mutator protein
- Nucleotidyltransferase
- Nucleus
- Polymerase iota
- Schiff base
- Transferase
- Transferase-dna complex
- Y-family polymerase