1m1p
From Proteopedia
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P21 crystal structure of the tetraheme cytochrome c3 from Shewanella oneidensis MR1
Overview
The genus Shewanella produces a unique small tetraheme cytochrome c that, is implicated in the iron oxide respiration pathway. It is similar in heme, content and redox potential to the well known cytochromes c(3) but related, in structure to the cytochrome c domain of soluble fumarate reductases, from Shewanella sp. We report the crystal structure of the small tetraheme, cytochrome c from Shewanella oneidensis MR-1 in two crystal forms and two, redox states. The overall fold and heme core are surprisingly different, from the soluble fumarate reductase structures. The high resolution, obtained for an oxidized orthorhombic crystal (0.97 A) revealed several, flexible regions. Comparison of the six monomers in the oxidized, monoclinic space group (1.55 A) indicates flexibility in the C-terminal, region containing heme IV. The reduced orthorhombic crystal structure, (1.02 A) revealed subtle differences in the position of several residues, resulting in decreased solvent accessibility of hemes and the withdrawal, of a positive charge from the molecular surface. The packing between, monomers indicates that intermolecular electron transfer between any heme, pair is possible. This suggests there is no unique site of electron, transfer on the surface of the protein and that electron transfer partners, may interact with any of the hemes, a process termed, "electron-harvesting." This optimizes the efficiency of intermolecular, electron transfer by maximizing chances of productive collision with redox, partners.
About this Structure
1M1P is a Single protein structure of sequence from Shewanella oneidensis with SO4 and HEM as ligands. Full crystallographic information is available from OCA.
Reference
Crystal structures at atomic resolution reveal the novel concept of "electron-harvesting" as a role for the small tetraheme cytochrome c., Leys D, Meyer TE, Tsapin AS, Nealson KH, Cusanovich MA, Van Beeumen JJ, J Biol Chem. 2002 Sep 20;277(38):35703-11. Epub 2002 Jun 21. PMID:12080059
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