Catalytic mechanism of DNA topoisomerase IB Journal Article
| Authors: | Krogh, B. O.; Shuman, S. |
| Article Title: | Catalytic mechanism of DNA topoisomerase IB |
| Abstract: | Type IB topoisomerases and tyrosine recombinases are structurally homologous strand transferases that act through DNA-(3'-phosphotyrosyl)-enzyme intermediates. A constellation of conserved amino acids (Arg-130, Lys-167, Arg-223, and His-265 in vaccinia topoisomerase) catalyzes transesterification of tyrosine to the scissile phosphodiester. We used 5'-bridging phosphorothiolate-modified DNAs to implicate Lys-167 as a general acid catalyst. The lower pK(a) of the 5'-S leaving group versus 5'-O restored activity to the K167A mutant, whereas there was no positive thio effect for mutants R223A and H265A. The lysine is located atop a flexible hairpin loop, and it shifts into the minor groove upon DNA binding. Coupling of conformational changes in a general acid loop to covalent catalysis of phosphoryl transfer is one of several mechanistic features shared by the topoisomerase/recombinase and protein phosphatase superfamilies. |
| Keywords: | human cell; mutation; amino acid substitution; enzyme activity; tyrosine; dna; regulatory mechanism; conserved sequence; molecular sequence data; kinetics; enzyme analysis; vaccinia virus; base sequence; models, molecular; conformational transition; catalysis; dna binding; enzyme structure; lysine; arginine; histidine; dna cleavage; dna topoisomerase; dna topoisomerases, type i; viral proteins; vaccinia; amino acid composition; binding kinetics; human; article; interactions with dna |
| Journal Title: | Molecular Cell |
| Volume: | 5 |
| Issue: | 6 |
| ISSN: | 1097-2765 |
| Publisher: | Cell Press |
| Date Published: | 2000-06-01 |
| Start Page: | 1035 |
| End Page: | 1041 |
| Language: | English |
| PUBMED: | 10911997 |
| PROVIDER: | scopus |
| DOI: | 10.1016/S1097-2765(00)80268-3 |
| DOI/URL: | |
| Notes: | Export Date: 18 November 2015 -- Source: Scopus |
Altmetric
Citation Impact
BMJ Impact Analytics
Related MSK Work