Banci Lucia, Bertini Ivano, Cefaro Chiara, Ciofi-Baffoni Simone, Gallo Angelo, Martinelli Manuele, Sideris Dionisia P, Katrakili Nitsa, Tokatlidis Kostas
Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019, Sesto Fiorentino, Florence, Italy.
Nat Struct Mol Biol. 2009 Feb;16(2):198-206. doi: 10.1038/nsmb.1553. Epub 2009 Feb 1.
MIA40 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在线粒体内膜间隙的氧化蛋白折叠过程中发挥关键作用。我们展示了人MIA40的溶液结构及其作为氧化折叠催化剂的机制。MIA40具有一个由66个残基组成的折叠结构域，该结构域由一个α-螺旋发夹核心组成，通过两个结构二硫键和一个刚性的N端盖子稳定，具有一个特征性的CPC基序，可将其二硫键捐赠给底物。CPC活性位点可被溶剂接触，且位于一个疏水裂缝附近。其第二个半胱氨酸（Cys55）在体内至关重要，对于与底物形成混合二硫键至关重要。疏水裂缝作为底物结合结构域，该结构域的突变在体内是致命的，并在体外消除结合。MIA40代表一种与硫氧还蛋白无关的最小氧化还原酶，具有一个易于作用的CPC氧化还原活性位点，可确保其在线粒体氧化折叠中的催化功能。
