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Bypass of the Major Alkylative DNA Lesion by Human DNA Polymerase η

A wide range of endogenous and exogenous alkylating agents attack DNA to generate various alkylation adducts. N7-methyl-2-deoxyguanosine (Fm7dG) is the most abundant alkylative DNA lesion. If not repaired, Fm7dG can undergo spontaneous depurination, imidazole ring-opening, or bypass by translesion s...

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Autores principales: Koag, Myong-Chul, Jung, Hunmin, Kou, Yi, Lee, Seongmin
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6864850/
https://www.ncbi.nlm.nih.gov/pubmed/31683505
http://dx.doi.org/10.3390/molecules24213928
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author Koag, Myong-Chul
Jung, Hunmin
Kou, Yi
Lee, Seongmin
author_facet Koag, Myong-Chul
Jung, Hunmin
Kou, Yi
Lee, Seongmin
author_sort Koag, Myong-Chul
collection PubMed
description A wide range of endogenous and exogenous alkylating agents attack DNA to generate various alkylation adducts. N7-methyl-2-deoxyguanosine (Fm7dG) is the most abundant alkylative DNA lesion. If not repaired, Fm7dG can undergo spontaneous depurination, imidazole ring-opening, or bypass by translesion synthesis DNA polymerases. Human DNA polymerase η (polη) efficiently catalyzes across Fm7dG in vitro, but its structural basis is unknown. Herein, we report a crystal structure of polη in complex with templating Fm7dG and an incoming nonhydrolyzable dCTP analog, where a 2′-fluorine-mediated transition destabilization approach was used to prevent the spontaneous depurination of Fm7dG. The structure showed that polη readily accommodated the Fm7dG:dCTP base pair with little conformational change of protein and DNA. In the catalytic site, Fm7dG and dCTP formed three hydrogen bonds with a Watson–Crick geometry, indicating that the major keto tautomer of Fm7dG is involved in base pairing. The polη-Fm7dG:dCTP structure was essentially identical to the corresponding undamaged structure, which explained the efficient bypass of the major methylated lesion. Overall, the first structure of translesion synthesis DNA polymerase bypassing Fm7dG suggests that in the catalytic site of Y-family DNA polymerases, small N7-alkylguanine adducts may be well tolerated and form the canonical Watson–Crick base pair with dCTP through their keto tautomers.
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spelling pubmed-68648502019-12-06 Bypass of the Major Alkylative DNA Lesion by Human DNA Polymerase η Koag, Myong-Chul Jung, Hunmin Kou, Yi Lee, Seongmin Molecules Article A wide range of endogenous and exogenous alkylating agents attack DNA to generate various alkylation adducts. N7-methyl-2-deoxyguanosine (Fm7dG) is the most abundant alkylative DNA lesion. If not repaired, Fm7dG can undergo spontaneous depurination, imidazole ring-opening, or bypass by translesion synthesis DNA polymerases. Human DNA polymerase η (polη) efficiently catalyzes across Fm7dG in vitro, but its structural basis is unknown. Herein, we report a crystal structure of polη in complex with templating Fm7dG and an incoming nonhydrolyzable dCTP analog, where a 2′-fluorine-mediated transition destabilization approach was used to prevent the spontaneous depurination of Fm7dG. The structure showed that polη readily accommodated the Fm7dG:dCTP base pair with little conformational change of protein and DNA. In the catalytic site, Fm7dG and dCTP formed three hydrogen bonds with a Watson–Crick geometry, indicating that the major keto tautomer of Fm7dG is involved in base pairing. The polη-Fm7dG:dCTP structure was essentially identical to the corresponding undamaged structure, which explained the efficient bypass of the major methylated lesion. Overall, the first structure of translesion synthesis DNA polymerase bypassing Fm7dG suggests that in the catalytic site of Y-family DNA polymerases, small N7-alkylguanine adducts may be well tolerated and form the canonical Watson–Crick base pair with dCTP through their keto tautomers. MDPI 2019-10-31 /pmc/articles/PMC6864850/ /pubmed/31683505 http://dx.doi.org/10.3390/molecules24213928 Text en © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Koag, Myong-Chul
Jung, Hunmin
Kou, Yi
Lee, Seongmin
Bypass of the Major Alkylative DNA Lesion by Human DNA Polymerase η
title Bypass of the Major Alkylative DNA Lesion by Human DNA Polymerase η
title_full Bypass of the Major Alkylative DNA Lesion by Human DNA Polymerase η
title_fullStr Bypass of the Major Alkylative DNA Lesion by Human DNA Polymerase η
title_full_unstemmed Bypass of the Major Alkylative DNA Lesion by Human DNA Polymerase η
title_short Bypass of the Major Alkylative DNA Lesion by Human DNA Polymerase η
title_sort bypass of the major alkylative dna lesion by human dna polymerase η
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6864850/
https://www.ncbi.nlm.nih.gov/pubmed/31683505
http://dx.doi.org/10.3390/molecules24213928
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