2hj3
From Proteopedia
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Structure of the Arabidopsis Thaliana Erv1 Thiol Oxidase
Overview
The ERV/ALR sulfhydryl oxidase domain is a versatile module adapted for, catalysis of disulfide bond formation in various organelles and biological, settings. Its four-helix bundle structure juxtaposes a Cys-X-X-Cys, dithiol/disulfide motif with a bound flavin adenine dinucleotide (FAD), cofactor, enabling transfer of electrons from thiol substrates to, non-thiol electron acceptors. ERV/ALR family members contain an additional, di-cysteine motif outside the four-helix-bundle core. Although the, location and context of this "shuttle" disulfide differs among family, members, it is proposed to perform the same basic function of mediating, electron transfer from substrate to the enzyme active site. We have, determined by X-ray crystallography the structure of AtErv1, an ERV/ALR, enzyme that contains a Cys-X4-Cys shuttle disulfide and oxidizes, thioredoxin in vitro, and compared it to ScErv2, which has a Cys-X-Cys, shuttle and does not oxidize thioredoxin at an appreciable rate. The, AtErv1 shuttle disulfide is in a region of the structure that is, disordered and thus apparently mobile and exposed. This feature may, facilitate access of protein substrates to the shuttle disulfide. To test, whether the shuttle disulfide region is modular and can confer on other, enzymes oxidase activity toward new substrates, we generated chimeric, enzyme variants combining shuttle disulfide and core elements from AtErv1, and ScErv2 and monitored oxidation of thioredoxin by the chimeras. We, found that the AtErv1 shuttle disulfide region could indeed confer, thioredoxin oxidase activity on the ScErv2 core. Remarkably, various, chimeras containing the ScErv2 Cys-X-Cys shuttle disulfide were found to, function efficiently as well. Since neither the ScErv2 core nor the, Cys-X-Cys motif is therefore incapable of participating in oxidation of, thioredoxin, we conclude that wild-type ScErv2 has evolved to repress, activity on substrates of this type, perhaps in favor of a different, as, yet unknown, substrate.
About this Structure
2HJ3 is a Single protein structure of sequence from Arabidopsis thaliana with and as ligands. Full crystallographic information is available from OCA.
Reference
Gain of function in an ERV/ALR sulfhydryl oxidase by molecular engineering of the shuttle disulfide., Vitu E, Bentzur M, Lisowsky T, Kaiser CA, Fass D, J Mol Biol. 2006 Sep 8;362(1):89-101. Epub 2006 Aug 8. PMID:16893552
Page seeded by OCA on Tue Jan 29 20:22:14 2008
