Increasing occurrences and functional roles for high energy purine-pyrimidine base-pairs in nucleic acids.

ABSTRACT: There are a growing number of studies reporting the observation of purine-pyrimidine base-pairs that are seldom observed in unmodified nucleic acids because they entail the loss of energetically favorable interactions or require energetically costly base ionization or tautomerization. These high energy purine-pyrimidine base-pairs include G•C(+) and A•T Hoogsteen base-pairs, which entail ?180° rotation of the purine base in a Watson-Crick base-pair, protonation of cytosine N3, and constriction of the C1'-C1' distance by ?2.5?. Other high energy pure-pyrimidine base-pairs include G•T, G•U, and A•C mispairs that adopt Watson-Crick like geometry through either base ionization or tautomerization. Although difficult to detect and characterize using biophysical methods, high energy purine-pyrimidine base-pairs appear to be more common than once thought. They further expand the structural and functional diversity of canonical and non-canonical nucleic acid base-pairs.

SUBMITTER: Kimsey I 

PROVIDER: S-EPMC4048017 | biostudies-literature | 2014 Feb

REPOSITORIES: biostudies-literature