3a3c
Crystal structure of TIM40/MIA40 fusing MBP, C296S and C298S mutant
Structural highlights
FunctionMALE_ECOLI Involved in the high-affinity maltose membrane transport system MalEFGK. Initial receptor for the active transport of and chemotaxis toward maltooligosaccharides.MIA40_YEAST Required for the import and folding of small cysteine-containing proteins (small Tim) in the mitochondrial intermembrane space (IMS). Forms a redox cycle with ERV1 that involves a disulfide relay system. Precursor proteins to be imported into the IMS are translocated in their reduced form into the mitochondria. The oxidized form of 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 MIA40 is reoxidized by FAD-linked sulfhydryl oxidase ERV1.[1] [2] [3] [4] [5] [6] 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 PubMedThe mitochondrial intermembrane space (IMS) contains many small cysteine-bearing proteins, and their passage across the outer membrane and subsequent folding require recognition and disulfide bond transfer by an oxidative translocator Tim40/Mia40 in the inner membrane facing the IMS. Here we determined the crystal structure of the core domain of yeast Mia40 (Mia40C4) as a fusion protein with maltose-binding protein at a resolution of 3 A. The overall structure of Mia40C4 is a fruit-dish-like shape with a hydrophobic concave region, which accommodates a linker segment of the fusion protein in a helical conformation, likely mimicking a bound substrate. Replacement of the hydrophobic residues in this region resulted in growth defects and impaired assembly of a substrate protein. The Cys296-Cys298 disulfide bond is close to the hydrophobic concave region or possible substrate-binding site, so that it can mediate disulfide bond transfer to substrate proteins. These results are consistent with the growth phenotypes of Mia40 mutant cells containing Ser replacement of the conserved cysteine residues. Structural basis of yeast Tim40/Mia40 as an oxidative translocator in the mitochondrial intermembrane space.,Kawano S, Yamano K, Naoe M, Momose T, Terao K, Nishikawa S, Watanabe N, Endo T Proc Natl Acad Sci U S A. 2009 Aug 25;106(34):14403-7. Epub 2009 Aug 10. PMID:19667201[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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