Abstract
Gel migration and uranyl photoprobing have been used to study the effects of inosine and 2,6-diaminopurine (2,6-DAP) substitution on adenine-tract (A-tract) induced DNA curvature. Using a 10mer repeated sequence including five inosines we show by uranyl photoprobing that a narrow minor groove varying in phase with the helix repeat is not the cause of DNA curvature. Further, we have systematically studied by gel migration the effects on A-tract induced curvature of either single or full substitution with inosine and/or 2,6-DAP in a 5'-AAAAAGCCGC-3'sequence. DNA curvature is shown to increase when inosines are substituted for the guanosines in the sequence between the A-tracts. By comparing the effects of each monosubstitution it can be seen that when the G closest to the 3'-end of the A-tract is substituted the effect on DNA curvature is much stronger than when substitution is made at any other position. By contrast, curvature is abolished when 2,6-DAP residues are substituted for all adenines, and monosubstitution reveals that the effect of substituting a single adenine is strongest at the 3'-end of the A-tract. These results favor a model in which the curvature induced by an A-tract in DNA molecules is primarily located at the junction with the 3'-end of the A-tract, and this peculiar junction is created because the A-tract has a preference to form a non-B-DNA structure which builds up from the 5'-end.
| Originalsprog | Engelsk |
|---|---|
| Tidsskrift | Nucleic Acids Research |
| Vol/bind | 25 |
| Udgave nummer | 17 |
| Sider (fra-til) | 3497-502 |
| Antal sider | 6 |
| ISSN | 0305-1048 |
| Status | Udgivet - 1 sep. 1997 |