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PDBsum entry 3a3c
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Protein transport
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PDB id
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3a3c
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References listed in PDB file
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Key reference
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Title
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Structural basis of yeast tim40/mia40 as an oxidative translocator in the mitochondrial intermembrane space.
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Authors
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S.Kawano,
K.Yamano,
M.Naoé,
T.Momose,
K.Terao,
S.Nishikawa,
N.Watanabe,
T.Endo.
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Ref.
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Proc Natl Acad Sci U S A, 2009,
106,
14403-14407.
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PubMed id
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Abstract
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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.
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