Flexibility at Gly-194 is required for DNA cleavage and relaxation activity of Escherichia coli DNA topoisomerase I.

Abstract

The proposed mechanism of type IA DNA topoisomerase I includes conformational changes by the single enzyme polypeptide to allow binding of the G strand of the DNA substrate at the active site, and the opening or closing of the "gate" created on the G strand of DNA to the passing single or double DNA strand(s) through the cleaved G strand DNA. The shifting of an alpha helix upon G strand DNA binding has been observed from the comparison of the type IA DNA topoisomerase crystal structures. Site-directed mutagenesis of the strictly conserved Gly-194 at the N terminus of this alpha helix in Escherichia coli DNA topoisomerase I showed that flexibility around this glycine residue is required for DNA cleavage and relaxation activity and supports a functional role for this hinge region in the enzyme conformational change.

Cite this paper

@article{Cheng2004FlexibilityAG, title={Flexibility at Gly-194 is required for DNA cleavage and relaxation activity of Escherichia coli DNA topoisomerase I.}, author={Bokun Cheng and Jingyang Feng and Sharvari Gadgil and Y. C. Tse-Dinh}, journal={The Journal of biological chemistry}, year={2004}, volume={279 10}, pages={8648-54} }