2gsa
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CRYSTAL STRUCTURE OF GLUTAMATE-1-SEMIALDEHYDE AMINOMUTASE (AMINOTRANSFERASE, WILD-TYPE FORM)
OverviewOverview
The three-dimensional structure of glutamate-1-semialdehyde aminomutase, (EC 5.4.3.8), an alpha2-dimeric enzyme from Synechococcus, has been, determined by x-ray crystallography using heavy atom derivative phasing., The structure, refined at 2.4-A resolution to an R-factor of 18.7% and, good stereochemistry, explains many of the enzyme's unusual specificity, and functional properties. The overall fold is that of aspartate, aminotransferase and related B6 enzymes, but it also has specific, features. The structure of the complex with gabaculine, a substrate, analogue, shows unexpectedly that the substrate binding site involves, residues from the N-terminal domain of the molecule, notably Arg-32., Glu-406 is suitably positioned to repel alpha-carboxylic acids, thereby, suggesting a basis for the enzyme's reaction specificity. The subunits, show asymmetry in cofactor binding and in the mobilities of the residues, 153-181. In the unliganded enzyme, one subunit has the cofactor bound as, an aldimine of pyridoxal phosphate with Lys-273 and, in this subunit, residues 153-181 are disordered. In the other subunit in which the, cofactor is not covalently bound, residues 153-181 are well defined., Consistent with the crystallographically demonstrated asymmetry, a form of, the enzyme in which both subunits have pyridoxal phosphate bound to, Lys-273 through a Schiff base showed biphasic reduction by borohydride in, solution. Analysis of absorption spectra during reduction provided, evidence of communication between the subunits. The crystal structure of, the reduced form of the enzyme shows that, despite identical cofactor, binding in each monomer, the structural asymmetry at residues 153-181, remains.
About this StructureAbout this Structure
2GSA is a Single protein structure of sequence from Synechococcus sp. with PMP and PLP as ligands. Active as Glutamate-1-semialdehyde 2,1-aminomutase, with EC number 5.4.3.8 Known structural/functional Sites: and . Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of glutamate-1-semialdehyde aminomutase: an alpha2-dimeric vitamin B6-dependent enzyme with asymmetry in structure and active site reactivity., Hennig M, Grimm B, Contestabile R, John RA, Jansonius JN, Proc Natl Acad Sci U S A. 1997 May 13;94(10):4866-71. PMID:9144156
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