Tim18p is a new component of the Tim54p-Tim22p translocon in the mitochondrial inner membrane

Mol Biol Cell. 2000 Jan;11(1):103-16. doi: 10.1091/mbc.11.1.103.

Abstract

The mitochondrial inner membrane contains two separate translocons: one required for the translocation of matrix-targeted proteins (the Tim23p-Tim17p complex) and one for the insertion of polytopic proteins into the mitochondrial inner membrane (the Tim54p-Tim22p complex). To identify new members of the Tim54p-Tim22p complex, we screened for high-copy suppressors of the temperature-sensitive tim54-1 mutant. We identified a new gene, TIM18, that encodes an integral protein of the inner membrane. The following genetic and biochemical observations suggest that the Tim18 protein is part of the Tim54p-Tim22p complex in the inner membrane: multiple copies of TIM18 suppress the tim54-1 growth defect; the tim18::HIS3 disruption is synthetically lethal with tim54-1; Tim54p and Tim22p can be coimmune precipitated with the Tim18 protein; and Tim18p, along with Tim54p and Tim22p, is detected in an approximately 300-kDa complex after blue native electrophoresis. We propose that Tim18p is a new component of the Tim54p-Tim22p machinery that facilitates insertion of polytopic proteins into the mitochondrial inner membrane.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antiporters*
  • Base Sequence
  • Binding Sites
  • Biological Transport
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Cell Division
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Hydro-Lyases / genetics
  • Hydro-Lyases / metabolism
  • Intracellular Membranes / metabolism*
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Membrane Transport Proteins*
  • Mitochondria / metabolism*
  • Mitochondrial Membrane Transport Proteins*
  • Mitochondrial Precursor Protein Import Complex Proteins
  • Molecular Sequence Data
  • Rabbits
  • Saccharomyces cerevisiae / cytology
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins*

Substances

  • Antiporters
  • Carrier Proteins
  • Fungal Proteins
  • Membrane Proteins
  • Membrane Transport Proteins
  • Mitochondrial Membrane Transport Proteins
  • Mitochondrial Precursor Protein Import Complex Proteins
  • Saccharomyces cerevisiae Proteins
  • TIM22 protein, S cerevisiae
  • TIM54 protein, S cerevisiae
  • Tim18 protein, S cerevisiae
  • Hydro-Lyases
  • imidazoleglycerolphosphate dehydratase