Motion in Aspartate Amino Transferase (AAT) [aat]

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Classification Known Domain Motion, Shear Mechanism [D-s-2]

Structures 1AMA Conformation 2 [ PartsList ] 9AAT Conformation 1 [ PartsList ]

Description Shear motion at 2 interfaces combined with hinge in a kinked helix. The domain motion is mainly the result of just two shear motions, which occur in perpendicular directions. AAT has an active site situated between a large and a small domain, and on substrate binding the small domain closes over the active site. The major shear motion involves a 13 degree rotation of the the small domain relative to the large one. A secondary shear motion moves a helix on one side of the small domain in a direction perpendicular to both the interdomain interface and the direction of the of the other shear motion. With a 1.2 A shift and a 10 degree rotation, it drops down to cover the active site. The shear motions in AAT are facilitated by a hinge motion in a long interdomain helix. This helix is kinked by 17 degrees in the open form and changes its kink angle by 12 degrees on closure.

Particular values describing motion Experimental Methods = x (Traditional x-ray) Creation Date = 19970822 Modification Date = 19970822

References E Hohenester and J N Jansonius (1994). Crystalline Mitochondrial Aspartate Aminotransferase Exists in Only Two Conformations. J. Mol. Biol. 236:963-968. [Medline info for 11340196] C A McPhalen, M G Vincent and J N Jansonius (1992). X-ray structure refinement and comparison of 3 forms of mitochondrial aspartate-aminotransferase. J. Mol. Biol. 225: 495-517. [Medline info for 92395661]

Data and Graphics Graphic-1 The kinking helix.

GO terms associated with structures Molecular function transaminase activity, transferase activity, transferring nitrogenous groups, catalytic activity Biological process biosynthesis, amino acid metabolism

Morphs

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Best representative Morph Morph name Structure #1 Structure #2 Residues [ ] [ ]

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Copyright 1995-2005 M. Gerstein, W. Krebs, S. Flores, N. Echols, and others
Email: Mark.Gerstein _at_ yale.edu