Increasing occurrences and functional roles for high energy purine-pyrimidine base-pairs in nucleic acids.
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 ∼2.5Å. 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.
Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, United States.
Isaac
I
Kimsey
Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, United States. Electronic address: hashim.al.hashimi@duke.edu.
Hashim M
HM
Al-Hashimi
D000818:Animals; D020029:Base Pairing; D004247:DNA / Q000737:chemistry*; D006801:Humans; D007536:Isomerism; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D011687:Purines / Q000737:chemistry*; D011743:Pyrimidines / Q000737:chemistry*
D011687:Purines; D011743:Pyrimidines; D004247:DNA; C030986:pyrimidine; C030985:purine