Structural basis of yeast Tim40/Mia40 as an oxidative translocator in the mitochondrial intermembrane space.
The 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.
Kawano
Shin
S
Department of Chemistry, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan.
Yamano
Koji
K
Naoé
Mari
M
Momose
Takaki
T
Terao
Kayoko
K
Nishikawa
Shuh-ichi
S
Watanabe
Nobuhisa
N
Endo
Toshiya
T
D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D003460:Crystallization; D003545:Cysteine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004220:Disulfides / Q000737:chemistry; D005816:Genetic Complementation Test; D057927:Hydrophobic and Hydrophilic Interactions; D015151:Immunoblotting; D058619:Maltose-Binding Proteins; D033681:Mitochondrial Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051336:Mitochondrial Membranes / Q000378:metabolism*; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D008958:Models, Molecular; D009154:Mutation; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D055672:Static Electricity; D014961:X-Ray Diffraction
D002352:Carrier Proteins; D004220:Disulfides; C495320:MIA40 protein, S cerevisiae; D058619:Maltose-Binding Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D003545:Cysteine