3igc is a 4 chain structure with sequence from Variola virus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
Poxviruses encode their own type IB topoisomerases (TopIBs), which release superhelical tension generated by replication and transcription of their genomes. To investigate the reaction catalyzed by viral TopIBs, we have determined the structure of a variola virus topoisomerase-DNA complex trapped as a vanadate transition state mimic. The structure reveals how the viral TopIB enzymes are likely to position the DNA duplex for ligation following relaxation of supercoils and identifies the sources of friction observed in single-molecule experiments that argue against free rotation. The structure also identifies a conformational change in the leaving group sugar that must occur prior to cleavage and reveals a mechanism for promoting ligation following relaxation of supercoils that involves an Asp-minor groove interaction. Overall, the new structural data support a common catalytic mechanism for the TopIB superfamily but indicate distinct methods for controlling duplex rotation in the small versus large enzyme subfamilies.
Insights from the structure of a smallpox virus topoisomerase-DNA transition state mimic.,Perry K, Hwang Y, Bushman FD, Van Duyne GD Structure. 2010 Jan 13;18(1):127-37. PMID:20152159[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
↑ Perry K, Hwang Y, Bushman FD, Van Duyne GD. Insights from the structure of a smallpox virus topoisomerase-DNA transition state mimic. Structure. 2010 Jan 13;18(1):127-37. PMID:20152159 doi:10.1016/j.str.2009.10.020
