2m2w: Difference between revisions

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== Function ==
== Function ==
[https://www.uniprot.org/uniprot/DPOLX_ASFB7 DPOLX_ASFB7] Error-prone polymerase lacking a proofreading 3'-5' exonuclease which plays a role in viral DNA repair. Specifically binds intermediates in the single-nucleotide base-excision repair process. Also catalyzes DNA polymerization with low nucleotide-insertion fidelity. Together with the viral DNA ligase, fills the single nucleotide gaps generated by the AP endonuclease.<ref>PMID:12595253</ref> <ref>PMID:11685239</ref>  
[https://www.uniprot.org/uniprot/DPOLX_ASFB7 DPOLX_ASFB7] Error-prone polymerase lacking a proofreading 3'-5' exonuclease which plays a role in viral DNA repair. Specifically binds intermediates in the single-nucleotide base-excision repair process. Also catalyzes DNA polymerization with low nucleotide-insertion fidelity. Together with the viral DNA ligase, fills the single nucleotide gaps generated by the AP endonuclease.<ref>PMID:12595253</ref> <ref>PMID:11685239</ref>  
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== Publication Abstract from PubMed ==
A dogma for DNA polymerase catalysis is that the enzyme binds DNA first, followed by MgdNTP. This mechanism contributes to the selection of correct dNTP by Watson-Crick base pairing, but it cannot explain how low-fidelity DNA polymerases overcome Watson-Crick base pairing to catalyze non-Watson-Crick dNTP incorporation. DNA polymerase X from the deadly African swine fever virus (Pol X) is a half-sized repair polymerase that catalyzes efficient dG:dGTP incorporation in addition to correct repair. Here we report the use of solution structures of Pol X in the free, binary (Pol X:MgdGTP), and ternary (Pol X:DNA:MgdGTP with dG:dGTP non-Watson-Crick pairing) forms, along with functional analyses, to show that Pol X uses multiple unprecedented strategies to achieve the mutagenic dG:dGTP incorporation. Unlike high fidelity polymerases, Pol X can prebind purine MgdNTP tightly and undergo a specific conformational change in the absence of DNA. The prebound MgdGTP assumes an unusual syn conformation stabilized by partial ring stacking with His115. Upon binding of a gapped DNA, also with a unique mechanism involving primarily helix alphaE, the prebound syn-dGTP forms a Hoogsteen base pair with the template anti-dG. Interestingly, while Pol X prebinds MgdCTP weakly, the correct dG:dCTP ternary complex is readily formed in the presence of DNA. H115A mutation disrupted MgdGTP binding and dG:dGTP ternary complex formation but not dG:dCTP ternary complex formation. The results demonstrate the first solution structural view of DNA polymerase catalysis, a unique DNA binding mode, and a novel mechanism for non-Watson-Crick incorporation by a low-fidelity DNA polymerase.
How a Low-Fidelity DNA Polymerase Chooses Non-Watson-Crick from Watson-Crick Incorporation.,Wu WJ, Su MI, Wu JL, Kumar S, Lim LH, Wang CW, Nelissen FH, Chen MC, Doreleijers JF, Wijmenga SS, Tsai MD J Am Chem Soc. 2014 Mar 21. PMID:24617852<ref>PMID:24617852</ref>
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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==See Also==
==See Also==

Latest revision as of 09:58, 1 May 2024

Ternary complex of ASFV Pol X with DNA and MgdGTPTernary complex of ASFV Pol X with DNA and MgdGTP

Structural highlights

2m2w is a 2 chain structure with sequence from African swine fever virus. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:Solution NMR
Ligands:, ,
Resources:FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

DPOLX_ASFB7 Error-prone polymerase lacking a proofreading 3'-5' exonuclease which plays a role in viral DNA repair. Specifically binds intermediates in the single-nucleotide base-excision repair process. Also catalyzes DNA polymerization with low nucleotide-insertion fidelity. Together with the viral DNA ligase, fills the single nucleotide gaps generated by the AP endonuclease.[1] [2]

See Also

References

  1. ↑ Garcia-Escudero R, Garcia-Diaz M, Salas ML, Blanco L, Salas J. DNA polymerase X of African swine fever virus: insertion fidelity on gapped DNA substrates and AP lyase activity support a role in base excision repair of viral DNA. J Mol Biol. 2003 Mar 7;326(5):1403-12. PMID:12595253
  2. ↑ Showalter AK, Byeon IJ, Su MI, Tsai MD. Solution structure of a viral DNA polymerase X and evidence for a mutagenic function. Nat Struct Biol. 2001 Nov;8(11):942-6. PMID:11685239 doi:10.1038/nsb1101-942
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