Mechanism of error-free DNA synthesis across N1-methyl-deoxyadenosine by human DNA polymerase-ι.
Sci Rep
; 7: 43904, 2017 03 08.
Article
de En
| MEDLINE
| ID: mdl-28272441
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.
Texte intégral:
1
Collection:
01-internacional
Base de données:
MEDLINE
Sujet principal:
ADN
/
Désoxyadénosine
/
DNA-directed DNA polymerase
Limites:
Humans
Langue:
En
Journal:
Sci Rep
Année:
2017
Type de document:
Article
Pays d'affiliation:
États-Unis d'Amérique