PDBsum entry 2fxt

Protein transport

PDB id: 2fxt

Contents

Protein chain

192 a.a.

References listed in PDB file

Key reference

Title

Crystal structure of yeast mitochondrial peripheral membrane protein tim44p c-Terminal domain.

Authors

R.Josyula, Z.Jin, Z.Fu, B.Sha.

Ref.

J Mol Biol, 2006, 359, 798-804. [DOI no: 10.1016/j.jmb.2006.04.020]

PubMed id

16647716

Abstract

The protein transports from the cell cytosol to the mitochondria matrix are carried out by the translocase of the outer membrane (TOM) complex and the translocase of the inner membrane (TIM) complexes. Tim44p is an essential mitochondrial peripheral membrane protein and a major component of TIM23 translocon. Tim44p can tightly associate with the inner mitochondrial membrane. To investigate the mechanism by which Tim44p functions in the TIM23 translocon to deliver the mitochondrial protein precursors, we have determined the crystal structure of the yeast Tim44p C-terminal domain to 3.2A resolution using the MAD method. The Tim44p C-terminal domain forms a monomer in the crystal structure and contains six alpha-helices and four antiparallel beta-strands. A large hydrophobic pocket was identified on the Tim44p structure surface. The N-terminal helix A1 is positively charged and the helix A1 protrudes out from the Tim44p main body.

Figure 2.
Figure 2. The large hydrophobic pocket on Tim44p surface. (a) Surface potential drawing of the Tim44p monomer molecule determined by GRASP.^21 The Tim44p is in the similar orientation as Figure 1(a). Blue and red denote positively and negatively charged regions, respectively. White indicates hydrophobic region. The scale bar of the surface potential is shown in the top of the Figure. The hydrophobic pocket is drawn in a red box. (b) The magnified version of the area within the red box in (a). The hydrophobic residues that are involved in forming the hydrophobic pocket are labeled. Figure 2. The large hydrophobic pocket on Tim44p surface. (a) Surface potential drawing of the Tim44p monomer molecule determined by GRASP.[4]^21 The Tim44p is in the similar orientation as [5]Figure 1(a). Blue and red denote positively and negatively charged regions, respectively. White indicates hydrophobic region. The scale bar of the surface potential is shown in the top of the Figure. The hydrophobic pocket is drawn in a red box. (b) The magnified version of the area within the red box in (a). The hydrophobic residues that are involved in forming the hydrophobic pocket are labeled.

Figure 3.
Figure 3. Sequence alignment of the Tim44p C-terminal domain from various species. Program Pileup from GCG package was utilized to align the Tim44p C-terminal domain sequence from S. cerevisiae with that from Homo sapiens, Mus musculus and Caenorhabditis elegans. The amino acid residues of yeast Tim44p are numbered above the alignment. The amino acid residues involved in forming the hydrophobic pocket of Tim44p are shown in bold. The conserved positively charged residues in helix A1 and A2 are underlined.

The above figures are reprinted by permission from Elsevier: J Mol Biol (2006, 359, 798-804) copyright 2006.