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2f4q

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[[Image:2f4q.gif|left|200px]]
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[[Image:2f4q.png|left|200px]]
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{{STRUCTURE_2f4q| PDB=2f4q | SCENE= }}
{{STRUCTURE_2f4q| PDB=2f4q | SCENE= }}
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'''Crystal Structure of Deinococcus radiodurans topoisomerase IB'''
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===Crystal Structure of Deinococcus radiodurans topoisomerase IB===
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==Overview==
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Type IB DNA topoisomerases are found in all eukarya, two families of eukaryotic viruses (poxviruses and mimivirus), and many genera of bacteria. They alter DNA topology by cleaving and resealing one strand of duplex DNA via a covalent DNA-(3-phosphotyrosyl)-enzyme intermediate. Bacterial type IB enzymes were discovered recently and are described as poxvirus-like with respect to their small size, primary structures, and bipartite domain organization. Here we report the 1.75-A crystal structure of Deinococcus radiodurans topoisomerase IB (DraTopIB), a prototype of the bacterial clade. DraTopIB consists of an amino-terminal (N) beta-sheet domain (amino acids 1-90) and a predominantly alpha-helical carboxyl-terminal (C) domain (amino acids 91-346) that closely resemble the corresponding domains of vaccinia virus topoisomerase IB. The five amino acids of DraTopIB that comprise the catalytic pentad (Arg-137, Lys-174, Arg-239, Asn-280, and Tyr-289) are preassembled into the active site in the absence of DNA in a manner nearly identical to the pentad configuration in human topoisomerase I bound to DNA. This contrasts with the apoenzyme of vaccinia topoisomerase, in which three of the active site constituents are either displaced or disordered. The N and C domains of DraTopIB are splayed apart in an "open" conformation, in which the surface of the catalytic domain containing the active site is exposed for DNA binding. A comparison with the human topoisomerase I-DNA cocrystal structure suggests how viral and bacterial topoisomerase IB enzymes might bind DNA circumferentially via movement of the N domain into the major groove and clamping of a disordered loop of the C domain around the helix.
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(as it appears on PubMed at http://www.pubmed.gov), where 16368685 is the PubMed ID number.
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{{ABSTRACT_PUBMED_16368685}}
==About this Structure==
==About this Structure==
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[[Category: Shuman, S.]]
[[Category: Shuman, S.]]
[[Category: Topoisomerase ib]]
[[Category: Topoisomerase ib]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 03:27:31 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 11:19:44 2008''

Revision as of 08:19, 29 July 2008

Image:2f4q.png

Template:STRUCTURE 2f4q

Crystal Structure of Deinococcus radiodurans topoisomerase IB

Template:ABSTRACT PUBMED 16368685

About this Structure

2F4Q is a Single protein structure of sequence from Deinococcus radiodurans. Full crystallographic information is available from OCA.

Reference

Crystal structure of a bacterial type IB DNA topoisomerase reveals a preassembled active site in the absence of DNA., Patel A, Shuman S, Mondragon A, J Biol Chem. 2006 Mar 3;281(9):6030-7. Epub 2005 Dec 19. PMID:16368685

Page seeded by OCA on Tue Jul 29 11:19:44 2008

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