Use of Oligodeoxyribonucleotides with Conformationally Constrained Abasic Sugar Targets To Probe the Mechanism of Base Flipping by HhaI DNA (Cytosine C5)-methyltransferase
| Autor: | Peiyuan Wang, Adam S. Brank, Marc C. Nicklaus, Alexander D. MacKerell, Victor E. Marquez, Nilesh K. Banavali, Judith K. Christman,‡ and |
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| Rok vydání: | 2000 |
| Předmět: | |
| Zdroj: | Journal of the American Chemical Society. 122:12422-12434 |
| ISSN: | 1520-5126 0002-7863 |
| Popis: | X-ray crystallographic studies of HhaI DNA (cytosine-C5)-methyltransferase (M.HhaI) covalently linked to methylated 5-fluorocytosine in DNA provided the first direct evidence that the cytosine residue targeted for methylation was “flipped” out of the helix during the transfer reaction. Subsequent studies indicated that removal of the target cytosine base, i.e., introduction of an abasic site, enhanced binding of M.HhaI to DNA and that the conformation of the sugar−phosphate backbone at the abasic site in the resultant complexes was the same as that of the sugar attached to a “flipped” cytosine. In the present study, pseudorotationally constrained sugar analogues, based on bicyclo[3.1.0]hexane templates, were placed in DNA duplexes as abasic target sites in the M.HhaI recognition sequence. Biochemical studies demonstrate that binding affinity of M.HhaI for abasic sites increases when the abasic target sugar analogue is constrained to the south conformation and decreases when it is constrained to the north ... |
| Databáze: | OpenAIRE |
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