1a41: Difference between revisions

[[Image:1a41.gif|left|200px]]<br /><applet load="1a41" size="350" color="white" frame="true" align="right" spinBox="true"  

Vaccinia DNA topoisomerase breaks and rejoins DNA strands through a DNA-(3'-phosphotyrosyl)-enzyme intermediate. A C-terminal catalytic domain, Topo(81-314), suffices for transesterification chemistry. The domain contains a constellation of five amino acids, conserved in all eukaryotic type IB topoisomerases, that catalyzes attack of the tyrosine nucleophile on the scissile phosphate. The structure of the catalytic domain, consisting of ten alpha helices and a three-strand beta sheet, resembles the catalytic domains of site-specific recombinases that act via a topoisomerase IB-like mechanism. The topoisomerase catalytic pentad is conserved in the tertiary structures of the recombinases despite scant sequence similarity overall. This implies that the catalytic domains of type IB topoisomerases and recombinases derive from a common ancestral strand transferase.

1A41 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Vaccinia_virus Vaccinia virus] with <scene name='pdbligand=SO4:'>SO4</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/DNA_topoisomerase DNA topoisomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.99.1.2 5.99.1.2] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1A41 OCA].  

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