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Title
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Crystallization of a 67 kDa fragment of Escherichia coli DNA topoisomerase I.
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Authors
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C.D.Lima,
J.C.Wang,
A.Mondragón.
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Ref.
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J Mol Biol, 1993,
232,
1213-1216.
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PubMed id
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Abstract
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Escherichia coli DNA topoisomerase I is a well-studied type I DNA topoisomerase
that catalyzes the breakage and rejoining of one DNA strand to allow passage of
the other strand. We have cloned and over-expressed a 67 kDa amino-terminal
fragment of the protein, and shown that it retains the ability of the intact
enzyme to cleave single-stranded DNA. High-quality crystals of the purified 67
kDa fragment have been obtained. The crystals belong to space group
P2(1)2(1)2(1), with cell dimensions a = 64.0 A, b = 79.9 A and c = 142.3 A. They
diffract to at least 2.8 A at low temperature and, when cooled to cryogenic
temperatures, to at least 1.9 A in a synchrotron source. A complete native data
set and two derivative data sets have been collected. A multiple isomorphous
replacement map to 3 A resolution shows clear secondary structural elements.
Final structure determination is in progress.
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