2k3j
From Proteopedia
The solution structure of human Mia40
Structural highlights
FunctionMIA40_HUMAN Functions as chaperone and catalyzes the formation of disulfide bonds in substrate proteins, such as COX17. Required for the import and folding of small cysteine-containing proteins (small Tim) in the mitochondrial intermembrane space (IMS). Precursor proteins to be imported into the IMS are translocated in their reduced form into the mitochondria. The oxidized form of CHCHD4/MIA40 forms a transient intermolecular disulfide bridge with the reduced precursor protein, resulting in oxidation of the precursor protein that now contains an intramolecular disulfide bond and is able to undergo folding in the IMS. Reduced CHCHD4/MIA40 is then reoxidized by GFER/ERV1 via a disulfide relay system.[1] [2] [3] [4] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedMIA40 has a key role in oxidative protein folding in the mitochondrial intermembrane space. We present the solution structure of human MIA40 and its mechanism as a catalyst of oxidative folding. MIA40 has a 66-residue folded domain made of an alpha-helical hairpin core stabilized by two structural disulfides and a rigid N-terminal lid, with a characteristic CPC motif that can donate its disulfide bond to substrates. The CPC active site is solvent-accessible and sits adjacent to a hydrophobic cleft. Its second cysteine (Cys55) is essential in vivo and is crucial for mixed disulfide formation with the substrate. The hydrophobic cleft functions as a substrate binding domain, and mutations of this domain are lethal in vivo and abrogate binding in vitro. MIA40 represents a thioredoxin-unrelated, minimal oxidoreductase, with a facile CPC redox active site that ensures its catalytic function in oxidative folding in mitochondria. MIA40 is an oxidoreductase that catalyzes oxidative protein folding in mitochondria.,Banci L, Bertini I, Cefaro C, Ciofi-Baffoni S, Gallo A, Martinelli M, Sideris DP, Katrakili N, Tokatlidis K Nat Struct Mol Biol. 2009 Feb;16(2):198-206. Epub 2009 Feb 1. PMID:19182799[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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