1d6m

From Proteopedia

(Difference between revisions)

Revision as of 07:30, 24 December 2014

CRYSTAL STRUCTURE OF E. COLI DNA TOPOISOMERASE III

Structural highlights

1d6m is a 1 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Activity:	DNA topoisomerase, with EC number 5.99.1.2
Resources:	FirstGlance, OCA, RCSB, PDBsum

Function

[TOP3_ECOLI] Releases the supercoiling and torsional tension of DNA introduced during the DNA replication and transcription by transiently cleaving and rejoining one strand of the DNA duplex. Introduces a single-strand break via transesterification at a target site in duplex DNA. The scissile phosphodiester is attacked by the catalytic tyrosine of the enzyme, resulting in the formation of a DNA-(5'-phosphotyrosyl)-enzyme intermediate and the expulsion of a 3'-OH DNA strand. The free DNA strand than undergoes passage around the unbroken strand thus removing DNA supercoils. Finally, in the religation step, the DNA 3'-OH attacks the covalent intermediate to expel the active-site tyrosine and restore the DNA phosphodiester backbone. TOP3 is a potent decatenase.^[1] ^[2]

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

Publication Abstract from PubMed

BACKGROUND: DNA topoisomerases are enzymes that change the topology of DNA. Type IA topoisomerases transiently cleave one DNA strand in order to pass another strand or strands through the break. In this manner, they can relax negatively supercoiled DNA and catenate and decatenate DNA molecules. Structural information on Escherichia coli DNA topoisomerase III is important for understanding the mechanism of this type of enzyme and for studying the mechanistic differences among different members of the same subfamily. RESULTS: The structure of the intact and fully active E. coli DNA topoisomerase III has been solved to 3.0 A resolution. The structure shows the characteristic fold of the type IA topoisomerases that is formed by four domains, creating a toroidal protein. There is remarkable structural similarity to the 67 kDa N-terminal fragment of E. coli DNA topoisomerase I, although the relative arrangement of the four domains is significantly different. A major difference is the presence of a 17 amino acid insertion in topoisomerase III that protrudes from the side of the central hole and could be involved in the catenation and decatenation reactions. The active site is formed by highly conserved amino acids, but the structural information and existing biochemical and mutagenesis data are still insufficient to assign specific roles to most of them. The presence of a groove in one side of the protein is suggestive of a single-stranded DNA (ssDNA)-binding region. CONCLUSIONS: The structure of E. coli DNA topoisomerase III resembles the structure of E. coli DNA topoisomerase I except for the presence of a positively charged loop that may be involved in catenation and decatenation. A groove on the side of the protein leads to the active site and is likely to be involved in DNA binding. The structure helps to establish the overall mechanism for the type IA subfamily of topoisomerases with greater confidence and expands the structural basis for understanding these proteins.

The structure of Escherichia coli DNA topoisomerase III.,Mondragon A, DiGate R Structure. 1999 Nov 15;7(11):1373-83. PMID:10574789^[3]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ DiGate RJ, Marians KJ. Molecular cloning and DNA sequence analysis of Escherichia coli topB, the gene encoding topoisomerase III. J Biol Chem. 1989 Oct 25;264(30):17924-30. PMID:2553698
↑ Srivenugopal KS, Lockshon D, Morris DR. Escherichia coli DNA topoisomerase III: purification and characterization of a new type I enzyme. Biochemistry. 1984 Apr 24;23(9):1899-906. PMID:6326814
↑ Mondragon A, DiGate R. The structure of Escherichia coli DNA topoisomerase III. Structure. 1999 Nov 15;7(11):1373-83. PMID:10574789

1 Structural highlights
2 Function
3 Evolutionary Conservation
4 Publication Abstract from PubMed
5 See Also
6 References

Proteopedia Page Contributors and Editors (what is this?)

OCA

Retrieved from "http://52.214.119.220/wiki/index.php/1d6m"

@@ Line 6: / Line 6: @@
 <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1d6m FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1d6m OCA], [http://www.rcsb.org/pdb/explore.do?structureId=1d6m RCSB], [http://www.ebi.ac.uk/pdbsum/1d6m PDBsum]</span></td></tr>
 </table>
+== Function ==
+[[http://www.uniprot.org/uniprot/TOP3_ECOLI TOP3_ECOLI]] Releases the supercoiling and torsional tension of DNA introduced during the DNA replication and transcription by transiently cleaving and rejoining one strand of the DNA duplex. Introduces a single-strand break via transesterification at a target site in duplex DNA. The scissile phosphodiester is attacked by the catalytic tyrosine of the enzyme, resulting in the formation of a DNA-(5'-phosphotyrosyl)-enzyme intermediate and the expulsion of a 3'-OH DNA strand. The free DNA strand than undergoes passage around the unbroken strand thus removing DNA supercoils. Finally, in the religation step, the DNA 3'-OH attacks the covalent intermediate to expel the active-site tyrosine and restore the DNA phosphodiester backbone. TOP3 is a potent decatenase.<ref>PMID:2553698</ref> <ref>PMID:6326814</ref>
 == Evolutionary Conservation ==
 [[Image:Consurf_key_small.gif|200px|right]]

1d6m

From Proteopedia

Revision as of 07:30, 24 December 2014

CRYSTAL STRUCTURE OF E. COLI DNA TOPOISOMERASE III

Structural highlights

Function

Evolutionary Conservation

Publication Abstract from PubMed

See Also

References

Contents

Proteopedia Page Contributors and Editors (what is this?)

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