Direct evidence for (G)O6···H₂-N4(C)⁺ hydrogen bonding in transient G(syn)-C⁺ and G(syn)-m⁵C⁺ Hoogsteen base pairs in duplex DNA from cytosine amino nitrogen off-resonance R_1ρ relaxation dispersion measurements.

ABSTRACT: NMR relaxation dispersion studies have shown that Watson-Crick G-C and A-T base pairs in duplex DNA exist in dynamic equilibrium with their Hoogsteen counterparts. Hoogsteen base pairs form through concurrent rotation of the purine base about the glycosidic bond from an anti to a syn conformation and constriction of the C1'-C1' distance across the base pair by ∼2 Å to allow Hoogsteen type hydrogen bonding. Owing to their unique structure, Hoogsteen base pairs can play important roles in DNA recognition, the accommodation, recognition, and repair of DNA damage, and in DNA replication. NMR relaxation dispersion experiments targeting imino nitrogen and protonated base and sugar carbons have provided insights into many structural features of transient Hoogsteen base pairs, including one of two

SUBMITTER: Rangadurai A 

PROVIDER: S-EPMC6933314 | biostudies-literature | 2019 Nov

REPOSITORIES: biostudies-literature