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PDBsum entry 2ciu
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Protein transport
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PDB id
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2ciu
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References listed in PDB file
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Key reference
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Title
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The tim21 binding domain connects the preprotein translocases of both mitochondrial membranes.
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Authors
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R.Albrecht,
P.Rehling,
A.Chacinska,
J.Brix,
S.A.Cadamuro,
R.Volkmer,
B.Guiard,
N.Pfanner,
K.Zeth.
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Ref.
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EMBO Rep, 2006,
7,
1233-1238.
[DOI no: ]
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PubMed id
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Abstract
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Proteins destined for the mitochondrial matrix are imported by the translocase
of the outer membrane--the TOM complex--and the presequence translocase of the
inner membrane--the TIM23 complex. At present, there is no structural
information on components of the presequence translocase. Tim21, a subunit of
the presequence translocase consisting of a membrane anchor and a
carboxy-terminal domain exposed to the intermembrane space, directly connects
the TOM and TIM23 complexes by binding to the intermembrane space domain of the
Tom22 receptor. We crystallized the binding domain of Tim21 of Saccharomyces
cerevisiae and determined its structure at 1.6 A resolution. The Tim21 structure
represents a new alpha/beta-mixed protein fold with two alpha-helices flanked by
an extended eight-stranded beta-sheet. We also identified a core sequence of
Tom22 that binds to Tim21. Furthermore, negatively charged amino-acid residues
of Tom22 are important for binding to Tim21. Here we suggest a mechanism for the
TOM-TIM interaction.
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Figure 2.
Figure 2 Crystal structure of Tim21[IMS]. (A) Views of the
molecular structure of Tim21[IMS] (top) with labelled  -helices
(green) and  -strands
(red). Images were generated using Molscript (Kraulis, 1991).
Surface presentations of the Tim21[IMS] molecule are shown
(bottom). Positive and negative potentials are coloured blue and
red, respectively. The images were generated using Grasp
(Nicholls et al, 1991). (B) Schematic representation of the
Tim21[IMS] fold. (C) Sequence of Tim21[IMS] and distribution of
secondary structure elements. (D) Hydrogen bonds (dashed)
between the helical part and the antiparallel -sheet.
Tim21[IMS], translocase of the inner membrane.
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Figure 3.
Figure 3 Surface presentations of Tim21[IMS]. Conserved
positively charged (blue), negatively charged (red), amphipathic
(green) and hydrophobic (black) residues on the surface are
shown. Ten unicellular organisms were compared (Saccharomyces
cerevisiae, Aspergillus fumigatus, Neurospora crassa, Candida
albicans, Kluyveromyces lactis, Aphis gossypii, Candida
glabrata, Desulfomusa hansenii, Yarrowia lipolytica,
Schizosaccharomyces pombe). Images were generated using DINO
(http://www.dino3d.org/). Tim21[IMS], translocase of the inner
membrane.
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The above figures are
reprinted
from an Open Access publication published by Macmillan Publishers Ltd:
EMBO Rep
(2006,
7,
1233-1238)
copyright 2006.
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