View source for 6plc


==Structure of human DNA polymerase eta complexed with 8OA in the template base paired with incoming non-hydrolyzable GTP==
<StructureSection load='6plc' size='340' side='right'caption='[[6plc]], [[Resolution|resolution]] 2.50&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6plc]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6PLC OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6PLC FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.5&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=A38:8-OXY+DEOXYADENOSINE-5-MONOPHOSPHATE'>A38</scene>, <scene name='pdbligand=GOL:GLYCEROL'>GOL</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=XG4:2-DEOXY-5-O-[(R)-HYDROXY{[(R)-HYDROXY(PHOSPHONOOXY)PHOSPHORYL]AMINO}PHOSPHORYL]GUANOSINE'>XG4</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=6plc FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6plc OCA], [https://pdbe.org/6plc PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6plc RCSB], [https://www.ebi.ac.uk/pdbsum/6plc PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6plc ProSAT]</span></td></tr>
</table>
== Disease ==
[https://www.uniprot.org/uniprot/POLH_HUMAN POLH_HUMAN] Defects in POLH are the cause of xeroderma pigmentosum variant type (XPV) [MIM:[https://omim.org/entry/278750 278750]; also designated as XP-V. Xeroderma pigmentosum (XP) is an autosomal recessive disease due to deficient nucleotide excision repair. It is characterized by hypersensitivity of the skin to sunlight, followed by high incidence of skin cancer and frequent neurologic abnormalities. XPV shows normal nucleotide excision repair, but an exaggerated delay in recovery of replicative DNA synthesis. Most XPV patients do not develop clinical symptoms and skin neoplasias until a later age. Clinical manifestations are limited to photo-induced deterioration of the skin and eyes.<ref>PMID:10385124</ref> <ref>PMID:10398605</ref> <ref>PMID:11032022</ref> <ref>PMID:11121129</ref> <ref>PMID:11773631</ref> 
== Function ==
[https://www.uniprot.org/uniprot/POLH_HUMAN POLH_HUMAN] 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. Plays an important role in the repair of UV-induced pyrimidine dimers. Depending on the context, it inserts the correct base, but causes frequent base transitions and transversions. May play a role in hypermutation at immunoglobulin genes. Forms a Schiff base with 5'-deoxyribose phosphate at abasic sites, but does not have lyase activity. Targets POLI to replication foci.<ref>PMID:10385124</ref> <ref>PMID:11743006</ref> <ref>PMID:11376341</ref> <ref>PMID:14630940</ref> <ref>PMID:14734526</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Reactive oxygen species generate the genotoxic 8-oxoguanine (oxoG) and 8-oxoadenine (oxoA) as major oxidative lesions. The mutagenicity of oxoG is attributed to the lesion's ability to evade the geometric discrimination of DNA polymerases by adopting Hoogsteen base pairing with adenine in a Watson-Crick-like geometry. Compared with oxoG, the mutagenesis mechanism of oxoA, which preferentially induces A-to-C mutations, is poorly understood. In the absence of protein contacts, oxoA:G forms a wobble conformation, the formation of which is suppressed in the catalytic site of most DNA polymerases. Interestingly, human DNA polymerase eta (poleta) proficiently incorporates dGTP opposite oxoA, suggesting the nascent oxoA:dGTP overcomes the geometric discrimination of poleta. To gain insights into oxoA-mediated mutagenesis, we determined crystal structures of poleta bypassing oxoA. When paired with dGTP, oxoA adopted a syn-conformation and formed Hoogsteen pairing while in a wobble geometry, which was stabilized by Gln38-mediated minor groove contacts to oxoA:dGTP. Gln38Ala mutation reduced misinsertion efficiency approximately 55-fold, indicating oxoA:dGTP misincorporation was promoted by minor groove interactions. Also, the efficiency of oxoA:dGTP insertion by the X-family polbeta decreased approximately 380-fold when Asn279-mediated minor groove contact to dGTP was abolished. Overall, these results suggest that, unlike oxoG, oxoA-mediated mutagenesis is greatly induced by minor groove interactions.

Mutagenesis mechanism of the major oxidative adenine lesion 7,8-dihydro-8-oxoadenine.,Koag MC, Jung H, Lee S Nucleic Acids Res. 2020 Apr 13. pii: 5819599. doi: 10.1093/nar/gkaa193. PMID:32282906<ref>PMID:32282906</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 6plc" style="background-color:#fffaf0;"></div>

==See Also==
*[[DNA polymerase 3D structures|DNA polymerase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Koag MC]]
[[Category: Lee S]]