NMR study of the conformation of the 2-aminopurine: Cytosine mismatch in DNA
- Lawrence Berkeley National Lab., CA (United States)
- Univ. of Southern California, Los Angeles, CA (United States); and others
DNA polymerase makes errors by misincorporating natural DNA bases and base analogs. Because of the wide variety of possible mismatches and the varying efficiency with which they are repaired, structural studies are necessary to understand in detail how these mispairs differ and can be distinguished from standard Watson-Crick base pairs. 2-Aminopurine (AP) is a highly mutagenic base analog. The objective of this study was to determine the geometry of the AP{center_dot}C mispair in DNA at neutral pH. Although several studies have focused on the AP{center_dot} mispair in DNA, there is not as of yet consensus on its structure. At least four models have been proposed for this mispair. Through the use of NMR spectroscopy with selective {sup 15}N-labeling of exocyclic amino nitrogens on bases of interest, we are able to resolve ambiguities in previous studies. We find here that, in two different DNA sequences, the AP{center_dot}C mispair at neutral and high pH is in a wobble geometry. The structure and stability of this base mispair is dependent upon the local base sequence. 48 refs., 4 figs., 1 tab.
- DOE Contract Number:
- FG05-86ER75281; AC03-76SF00098
- OSTI ID:
- 525815
- Journal Information:
- Biochemistry (Eaton), Journal Name: Biochemistry (Eaton) Journal Issue: 13 Vol. 35; ISSN 0006-2960; ISSN BICHAW
- Country of Publication:
- United States
- Language:
- English
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