PDBsum entry 3fp3

Transport protein

PDB id: 3fp3

Contents

Protein chain

498 a.a. *

Ligands

SO4 ×3

Metals

_CL ×4

Waters ×542

* Residue conservation analysis

PDB id:

3fp3

Name:

Transport protein

Title:

Crystal structure of tom71

Structure:

Tpr repeat-containing protein yhr117w. Chain: a. Fragment: unp residues 107-639. Engineered: yes

Source:

Saccharomyces cerevisiae. Yeast. Organism_taxid: 4932. Gene: yhr117w. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

1.98Å R-factor: 0.189 R-free: 0.227

Authors:

J.Li,X.Qian,J.Hu,B.Sha

Key ref:

J.Li et al. (2009). Molecular chaperone Hsp70/Hsp90 prepares the mitochondrial outer membrane translocon receptor Tom71 for preprotein loading. J Biol Chem, 284, 23852-23859. PubMed id: 19581297 DOI: 10.1074/jbc.M109.023986

Date:

03-Jan-09 Release date: 28-Jul-09

Protein chain

P38825  (TOM71_YEAST) -  Protein TOM71 from Saccharomyces cerevisiae (strain ATCC 204508 / S288c)

Seq: 639 a.a.

Struc: 498 a.a.

DOI no: 10.1074/jbc.M109.023986

J Biol Chem 284:23852-23859 (2009)

PubMed id: 19581297

Molecular chaperone Hsp70/Hsp90 prepares the mitochondrial outer membrane translocon receptor Tom71 for preprotein loading.

J.Li, X.Qian, J.Hu, B.Sha.

ABSTRACT

The preproteins targeted to the mitochondria are transported through the translocase of the outer membrane complex. Tom70/Tom71 is a major surface receptor of the translocase of the outer membrane complex for mitochondrial preproteins. The preproteins are escorted to Tom70/Tom71 by molecular chaperones Hsp70 and Hsp90. Here we present the high resolution crystal structures of Tom71 and the protein complexes between Tom71 and the Hsp70/Hsp90 C terminus. The crystal structures indicate that Tom70/Tom71 may exhibit two distinct states. In the closed state, the N-terminal domain of Tom70/Tom71 partially blocks the preprotein-binding pocket. In the open state, the N-terminal domain moves away, and the preprotein-binding pocket is fully exposed. The complex formation between the C-terminal EEVD motif of Hsp70/Hsp90 and Tom71 could lock Tom71 in the open state where the preprotein-binding pocket of Tom71 is ready to receive preproteins. The interactions between Hsp70/Hsp90 and Tom71 N-terminal domain generate conformational changes that may increase the volume of the preprotein-binding pocket. The complex formation of Hsp70/Hsp90 and Tom71 also generates significant domain rearrangement within Tom71, which may position the preprotein-binding pocket closer to Hsp70/Hsp90 to facilitate the preprotein transfer from the molecular chaperone to Tom71. Therefore, molecular chaperone Hsp70/Hsp90 may function to prepare the mitochondrial outer membrane receptor Tom71 for preprotein loading.

Selected figure(s)

Figure 4.
The conformational changes of Tom71 generated by Hsp70 binding.a, the N-terminal domain of Tom71 is superimposed with that in the Tom71-Hsp70 complex and they are shown by a ribbon drawing. The Tom71 N-terminal domain is in light blue. The Tom71 N-terminal domain within the Tom71-Hsp70 complex is in silver. The bound Hsp70 C-terminal peptide is in red. Helices A5, A6, and A7 are labeled in blue. Some residues of Tom71 involved in generating the conformational changes are labeled in black. Residues Lys^196, Arg^200, and Leu^199 of Tom71 involved in binding Hsp70 are labeled. The residues forming hydrophobic cluster to associate A5, A6, and A7 are labeled. Glu^206 and Arg^238 linking A5 and A7 by forming a salt bridge are also labeled. b, Cα trace drawings of yeast Tom71 structure and the Tom71-Hsp70 complex structure. The N-terminal domain of Tom71 is superimposed with that in the Tom71-Hsp70 complex structure. The molecules in this figure are in a similar orientation as in a. The uncomplexed Tom71 structure is in purple. In the Tom71-Hsp70 C terminus complex, Tom71 is in green, and the Hsp70 C terminus is in red. The N- and C-terminal domains of Tom71 are labeled. Helix A7 acting as the hinge to connect the N-and C-terminal domains of Tom71 is labeled.

Figure 5.
The cartoon drawing for the mechanism how Hsp70/Hsp90 prepares Tom70/Tom71 for preprotein loading.a, Tom70/Tom71 may exhibit two distinct states: the open and closed state. The Tom70/Tom71 molecule is shown in blue. The N- and C-terminal domains are labeled. The mitochondria outer membrane is shown in orange. b, the interactions between the Hsp70/Hsp90 C-terminal EEVD motif will lock the Tom70/Tom71 in the open state. The Hsp70/Hsp90 is shown in gold. The binding between Hsp70/Hsp90 and Tom71 could increase the volume of the preprotein-binding pocket. The complex formation might rotate the Tom71 C-terminal domain ∼20° back toward the closed state and therefore position the preprotein-binding pocket closer to the Hsp70/Hsp90. The Hsp70/Hsp90 EEVD motif is shown as a red arrow. The preprotein is shown as a green triangle. c, Hsp70/Hsp90 will then load the preprotein into the enlarged preprotein-binding pocket of Tom70/Tom71.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2009, 284, 23852-23859) copyright 2009.

Figures were selected by an automated process.