The ATPase Reaction Cycle of Yeast DNA Topoisomerase II
DNA topoisomerase II catalyzes the transport of one DNA duplex through a transient break in a second duplex using a complex ATP hydrolysis mechanism. Two key rates in the ATPase mechanism, ATP resynthesis and phosphate release, were investigated using 18 O exchange and stopped-flow phosphate release...
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Published in | The Journal of biological chemistry Vol. 276; no. 30; pp. 27893 - 27898 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
American Society for Biochemistry and Molecular Biology
27.07.2001
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Online Access | Get full text |
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Summary: | DNA topoisomerase II catalyzes the transport of one DNA duplex through a transient break in a second duplex using a complex
ATP hydrolysis mechanism. Two key rates in the ATPase mechanism, ATP resynthesis and phosphate release, were investigated
using 18 O exchange and stopped-flow phosphate release experiments, respectively. The 18 O exchange results showed that the rate of ATP resynthesis on the topoisomerase II active site was slow compared with the
rate of phosphate release. When topoisomerase II was bound to DNA, phosphate was released slowly, with a lag. Since each of
the preceding steps is known to occur rapidly, phosphate release is apparently a rate-determining step. The length of the
lag phase was unaffected by etoposide, indicating that inhibiting DNA religation inhibits the ATPase reaction cycle at some
step following phosphate release. By combining the 18 O exchange and phosphate release results, the rate constant for ATP resynthesis can be calculated as â¼0.5 s â
1 . These data support the mechanism of sequential hydrolysis of two ATP by DNA topoisomerase II. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1074/jbc.M102544200 |