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Guanine to inosine substitution leads to large increases in the population of a transient G·C Hoogsteen base pair.

ABSTRACT: We recently showed that Watson-Crick base pairs in canonical duplex DNA exist in dynamic equilibrium with G(syn)·C+ and A(syn)·T Hoogsteen base pairs that have minute populations of ∼1%. Here, using nuclear magnetic resonance R1ρ relaxation dispersion, we show that substitution of guanine with the naturally occurring base inosine results in an ∼17-fold increase in the population of transient Hoogsteen base pairs, which can be rationalized by the loss of a Watson-Crick hydrogen bond. These results provide further support for transient Hoogsteen base pairs and demonstrate that their population can increase significantly upon damage or chemical modification of the base.

SUBMITTER: Nikolova EN

PROVIDER: S-EPMC4245982 | biostudies-literature | 2014 Nov

REPOSITORIES: biostudies-literature

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Guanine to inosine substitution leads to large increases in the population of a transient G·C Hoogsteen base pair.

Nikolova Evgenia N EN Stull Frederick F Al-Hashimi Hashim M HM

Biochemistry 20141110 46

We recently showed that Watson-Crick base pairs in canonical duplex DNA exist in dynamic equilibrium with G(syn)·C+ and A(syn)·T Hoogsteen base pairs that have minute populations of ∼1%. Here, using nuclear magnetic resonance R1ρ relaxation dispersion, we show that substitution of guanine with the naturally occurring base inosine results in an ∼17-fold increase in the population of transient Hoogsteen base pairs, which can be rationalized by the loss of a Watson-Crick hydrogen bond. These result ...[more]

PMID: 25339065

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