PDBsum entry: 2guz

Chaperone, protein transport

PDB id: 2guz

Contents

Protein chains

(+ 2 more) 71 a.a. *

(+ 2 more) 65 a.a. *

Ligands

FLC ×4

Waters ×921

* Residue conservation analysis

PDB id:

2guz

Name:

Chaperone, protein transport

Title:

Structure of the tim14-tim16 complex of the mitochondrial protein import motor

Structure:

Mitochondrial import inner membrane translocase subunit tim14. Chain: a, c, e, g, i, k, m, o. Fragment: j-domain. Synonym: presequence translocated-associated motor subunit pam18. Engineered: yes. Mitochondrial import inner membrane translocase subunit tim16.

Source:

Saccharomyces cerevisiae. Baker's yeast. Organism_taxid: 4932. Gene: pam18, tim14. Expressed in: escherichia coli. Expression_system_taxid: 562. Gene: pam16, tim16. Expression_system_taxid: 562

Biol. unit:

Dimer (from PQS)

Resolution:

2.00Å R-factor: 0.208 R-free: 0.253

Authors:

D.Mokranjac,G.Bourenkov,K.Hell,W.Neupert,M.Groll

Key ref:

D.Mokranjac et al. (2006). Structure and function of Tim14 and Tim16, the J and J-like components of the mitochondrial protein import motor. EMBO J, 25, 4675-4685. PubMed id: 16977310 DOI: 10.1038/sj.emboj.7601334

Date:

02-May-06 Release date: 03-Oct-06

Protein chains

Q07914  (TIM14_YEAST) -  Mitochondrial import inner membrane translocase subunit TIM14

Seq: 168 a.a.

Struc: 71 a.a.*

Protein chains

P42949  (TIM16_YEAST) -  Mitochondrial import inner membrane translocase subunit TIM16

Seq: 149 a.a.

Struc: 65 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

 Gene Ontology (GO) functional annotation 

• Biochemical function: heat shock protein binding (1 term)

DOI no: 10.1038/sj.emboj.7601334

EMBO J 25:4675-4685 (2006)

PubMed id: 16977310

Structure and function of Tim14 and Tim16, the J and J-like components of the mitochondrial protein import motor.

D.Mokranjac, G.Bourenkov, K.Hell, W.Neupert, M.Groll.

ABSTRACT

The import motor of the mitochondrial translocase of the inner membrane (TIM23) mediates the ATP-dependent translocation of preproteins into the mitochondrial matrix by cycles of binding to and release from mtHsp70. An essential step of this process is the stimulation of the ATPase activity of mtHsp70 performed by the J cochaperone Tim14. Tim14 forms a complex with the J-like protein Tim16. The crystal structure of this complex shows that the conserved domains of the two proteins have virtually identical folds but completely different surfaces enabling them to perform different functions. The Tim14-Tim16 dimer reveals a previously undescribed arrangement of J and J-like domains. Mutations that destroy the complex between Tim14 and Tim16 are lethal demonstrating that complex formation is an essential requirement for the viability of cells. We further demonstrate tight regulation of the cochaperone activity of Tim14 by Tim16. The first crystal structure of a J domain in complex with a regulatory protein provides new insights into the function of the mitochondrial TIM23 translocase and the Hsp70 chaperone system in general.

Selected figure(s)

Figure 2.
Figure 2 Topology and charge patterns of Tim14 and Tim16. (A) Ribbon presentations of the J domain of Tim14 (left panel) and the J-like domain of Tim16 (central panel). For comparison, the J domain of DnaJ from E. coli is included (right panel). Helices I–III are indicated. HPD motifs in the J domains are presented as balls-and-sticks models and colored in yellow. Corresponding DKE motif in Tim16 is colored in gray. As compared to the J domain of DnaJ, Tim14 and Tim16 lack helix IV. (B) Superposition of the J and J-like domains of Tim14, Tim16 and DnaJ. (C) Surface representations of Tim14, Tim16 and DnaJ. Ribbon presentations of the same orientation are shown as insets. The domains are rotated clockwise by 80° relative to the representations in (A) to bring helix II to the front. Surface colors indicate positive (intense blue) and negative electrostatic potentials (intense red) with the scale bar giving the actual potentials in kT/e. Lys and Arg residues of Tim14 contributing to the positive surface charge distribution are indicated.

Figure 6.
Figure 6 Evolutionary conservation of Tim14 and Tim16. Sequence alignment of Tim14 (A) and Tim16 (B) with their homologues. Identical residues are shown as white letters on black background and similar residues are shaded in gray. The characteristic helices of the J domain fold are indicated below the alignments. The HPD motif is shown in yellow. Predicted transmembrane domain (TM) of Tim14 is underlined. Red/blue pentagons—Tim14/Tim16 residues forming the hydrophobic cores of the J/J-like domains; Yellow circles—Tim14 residues which form the positively charged surface for interaction with mtHsp70; green squares/diamonds—residues involved in polar/hydrophobic interactions between Tim14 and Tim16. The parts of Tim14 and Tim16, which were crystallized, are boxed.

The above figures are reprinted by permission from Macmillan Publishers Ltd: EMBO J (2006, 25, 4675-4685) copyright 2006.

Figures were selected by the author.