PDBsum entry 1om2

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Receptor/oxidoreductase complex PDB id
Protein chains
95 a.a. *
11 a.a. *
* Residue conservation analysis

References listed in PDB file
Key reference
Title Structural basis of presequence recognition by the mitochondrial protein import receptor tom20.
Authors Y.Abe, T.Shodai, T.Muto, K.Mihara, H.Torii, S.Nishikawa, T.Endo, D.Kohda.
Ref. Cell, 2000, 100, 551-560. [DOI no: 10.1016/S0092-8674(00)80691-1]
PubMed id 10721992
Most mitochondrial proteins are synthesized in the cytosol as precursor proteins with a cleavable N-terminal presequence and are imported into mitochondria. We report here the NMR structure of a general import receptor, rat Tom20, in a complex with a presequence peptide derived from rat aldehyde dehydrogenase. The cytosolic domain of Tom20 forms an all alpha-helical structure with a groove to accommodate the presequence peptide. The bound presequence forms an amphiphilic helical structure with hydrophobic leucines aligned on one side to interact with a hydrophobic patch in the Tom20 groove. Although the positive charges of the presequence are essential for import ability, presequence binding to Tom20 is mediated mainly by hydrophobic rather than ionic interactions.
Figure 3.
Figure 3. Structure of Δ50Tom20 in Complex with a Presequence Peptide, pALDH(12–22)(A) Sequence alignment of Δ50Tom20 and corresponding regions of Tom20 from other organisms (human, Caenorhabditis elegans, Neurospora crassa, and yeast Saccharomyces cerevisiae). The two acidic regions and the Q-rich region are shaded in red and yellow, respectively. The TPR motif is shown as a blue box with its consensus amino acids. α helices and flexible regions are drawn as cylinders and broken lines, respectively. The hydrophobic residues constituting the hydrophobic patch in the presequence binding groove are indicated with yellow triangles, and the hydrophilic residues in the periphery of the groove are colored in orange (Gln) and red (Glu) circles.(B) Overlay of the 20 final structures. The residues used for superimposing the different structures are colored in blue (Tom20) and red (presequence peptide), and the other residues are in gray (Tom20) and orange (presequence).(C) Ribbon model of Δ50Tom20 indicating the {^1H}-^15N heteronuclear NOE values (red to white; −0.9 vert, similar +0.9) measured in the absence of the presequence. Smaller NOE values imply faster motions.
Figure 5.
Figure 5. Representation of the Binding Groove of Δ50Tom20 and the Bound Presequence Peptide(A) Molecular surface of Δ50Tom20 (residues 57–124). Hydrophobic residues comprising the hydrophobic patch (Phe^70, Leu^71, Ile^74, Leu^106, Val^109, Leu^110, Thr^113), and Gln (Gln^67, Gln^75, Gln^102, Gln^104, Gln^105, Gln^108, Gln^111, and Gln^112) and Glu (Glu^78 and Glu^79) in the peripheral region are colored in yellow, orange, and red, respectively. The bound peptide is drawn as a tube with sidechains in magenta for Leu, blue for Arg, and cyan for others. N' and C' denote the N and C termini of the peptide, respectively.(B) Same structure viewed from an angle along the arrow shown in (A).
The above figures are reprinted by permission from Cell Press: Cell (2000, 100, 551-560) copyright 2000.
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