Guarding the genome: Electrostatic repulsion of water by DNA suppresses a potent nuclease activity of topoisomerase IB Journal Article
| Authors: | Tian, L.; Claeboe, C. D.; Hecht, S. M.; Shuman, S. |
| Article Title: | Guarding the genome: Electrostatic repulsion of water by DNA suppresses a potent nuclease activity of topoisomerase IB |
| Abstract: | Type IB topoisomerases cleave and rejoin DNA strands through a stable covalent DNA-(3′-phosphotyrosyl)-enzyme intermediate. The stability of the intermediate is a two-edged sword; it preserves genome integrity during supercoil relaxation, but it also reinforces the toxicity of drugs and lesions that interfere with the DNA rejoining step. Here, we identify a key determinant of the stability of the complex by showing that introduction of an Sp or Rp methylphosphonate linkage at the cleavage site transforms topoisomerase IB into a potent endonuclease. The nuclease reaction entails formation and surprisingly rapid hydrolysis of a covalent enzyme-DNA methylphosphonate intermediate. The ∼30,000-fold acceleration in the rate of hydrolysis of a methylphosphonate versus phosphodiester suggests that repulsion of water by the DNA phosphate anion suppresses the latent nuclease function of topoisomerase IB. These findings expose an Achilles' heel of topoisomerases as guardians of the genome, and they have broad implications for understanding enzymatic phosphoryl transfer. |
| Keywords: | nonhuman; protein function; phosphorylation; genome analysis; dna; genome; binding sites; molecular structure; water; endonuclease; hydrolysis; molecular conformation; electricity; dna topoisomerase; dna topoisomerases, type i; protein dna interaction; organophosphorus compounds; oligodeoxyribonucleotides; gene expression regulation, enzymologic; ester derivative; linkage analysis; covalent bond; endonucleases; electrostatics; methylphosphonic acid; article; achilles tendon |
| Journal Title: | Molecular Cell |
| Volume: | 12 |
| Issue: | 1 |
| ISSN: | 1097-2765 |
| Publisher: | Cell Press |
| Date Published: | 2003-07-01 |
| Start Page: | 199 |
| End Page: | 208 |
| Language: | English |
| DOI: | 10.1016/s1097-2765(03)00263-6 |
| PUBMED: | 12887905 |
| PROVIDER: | scopus |
| DOI/URL: | |
| Notes: | Export Date: 12 September 2014 -- Source: Scopus |
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