1vsk: Difference between revisions

Crystallographic studies of the catalytic core domain of avian sarcoma, virus integrase (ASV IN) have provided the most detailed picture so far of, the active site of this enzyme, which belongs to an important class of, targets for designing drugs against AIDS. Recently, crystals of an, inactive D64N mutant were obtained under conditions identical to those, used for the native enzyme. Data were collected at different pH values and, in the presence of divalent cations. Data were also collected at low pH, for the crystals of the native ASV IN core domain. In the structures of, native ASV IN at pH 6.0 and below, as well as in all structures of the, D64N mutants, the side chain of the active site residue Asx-64 (Asx, denotes Asn or Asp) is rotated by approximately 150 degrees around the, Calpha---Cbeta bond, compared with the structures at higher pH. In the new, structures, this residue makes hydrogen bonds with the amide group of, Asn-160, and thus, the usual metal-binding site, consisting of Asp-64, Asp-121, and Glu-157, is disrupted. Surprisingly, however, a single Zn2+, can still bind to Asp-121 in the mutant, without restoration of the, activity of the enzyme. These structures have elucidated an unexpected, mechanism of inactivation of the enzyme by lowering the pH or by mutation, in which a protonated side chain of Asx-64 changes its orientation and, interaction partner.

1VSK is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Rous_sarcoma_virus Rous sarcoma virus]. Active as [http://en.wikipedia.org/wiki/RNA-directed_DNA_polymerase RNA-directed DNA polymerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.7.49 2.7.7.49] Structure known Active Site: ACT. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1VSK OCA].  

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