1i1o
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(New page: 200px<br /><applet load="1i1o" size="450" color="white" frame="true" align="right" spinBox="true" caption="1i1o, resolution 2.0Å" /> '''ROOM TEMPERATURE CRYS...)
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Revision as of 14:51, 20 November 2007
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ROOM TEMPERATURE CRYSTAL STRUCTURE FLAVODOXIN D. VULGARIS MUTANT Y98H AT 2.0 ANG. RESOLUTION
Overview
The structures for two mutants at the Tyr98 site of Desulfovibrio vulgaris, flavodoxin have been determined. The first, a tyrosine-to-histidine (Y98H), variant, was determined at the moderately high resolution of 2.0 A, while, the tyrosine-to-tryptophan variant (Y98W) yielded very high resolution, data (beyond 1.5 A) allowing a detailed look at the water structure, alternate side-chain conformations and the planarity of the FMN. Both, structures were solved by molecular replacement beginning with the native, (P2A) coordinates as a starting point. The Y98H variant of D. vulgaris, flavodoxin crystallizes in space group P2(1)2(1)2(1), with unit-cell, parameters a = 41.96, b = 61.45, c = 57.04 A, while the Y98W mutant adopts, space group P2(1), with a = 41.29, b = 55.82, c = 32.52 A, beta = 100.68, degrees. Refinement for both mutants utilized PROLSQ followed by, for the, high-resolution Y98W structure, anisotropic refinement as implemented in, SHELXL. Final R factors of 17% for the Y98H mutant and 9.8% for the Y98W, mutant were obtained. For the high-resolution (1.5 A) Y98W mutant, 31,010, unique reflections were collected from a single crystal. The final model, includes 273 solvent molecules, with eight side chains assuming multiple, conformations. At this resolution, the detailed conformation of the FMN, can be observed, with both a bow and twist being noted. A comparison is, made between the two mutants and the different oxidation states of the, native flavodoxin. Although both mutants show similar E(2), (oxidized/semiquinone) one-electron redox potentials to the native, the, E(1) (semiquinone/hydroquinone) redox potential for the Y98H mutant is, significantly different from that of the Y98W variant and the native, protein. The surprising similarity in the folding of the polypeptide chain, 60--64 between the two mutants and the reduced states of the native is, discussed. The interaction between O61 and N5 in the flavin is discussed, because of the new conformation of this loop.
About this Structure
1I1O is a Single protein structure of sequence from Desulfovibrio vulgaris with FMN as ligand. Full crystallographic information is available from OCA.
Reference
Structures and comparison of the Y98H (2.0 A) and Y98W (1.5 A) mutants of flavodoxin (Desulfovibrio vulgaris)., Reynolds RA, Watt W, Watenpaugh KD, Acta Crystallogr D Biol Crystallogr. 2001 Apr;57(Pt 4):527-35. PMID:11264581
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