Domain structure and lipid interaction of recombinant yeast Tim44

Celeste Weiss, Wolfgang Oppliger, Guy Vergères, Rudy Demel, Paul Jenö, Martin Horst, Ben De Kruijff, Gottfried Schatz, Abdussalam Azem*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Tim44 is an essential component of the machinery that mediates the translocation of nuclear-encoded proteins across the mitochondrial inner membrane. It functions as a membrane anchor for the ATP-driven protein import motor whose other subunits are the mitochondrial 70-kDa heat-shock protein (mhsp70) and its nucleotide exchange factor, mGrpE. To understand how this motor is anchored to the inner membrane, we have overexpressed Tim44 in Escherichia coli and studied the properties of the pure protein and its interaction with model lipid membranes. Limited proteolysis and analytical ultracentrifugation indicate that Tim44 is an elongated monomer with a stably folded C-terminal domain. The protein binds strongly to liposomes composed of phosphatidylcholine and cardiolipin but only weakly to liposomes containing phosphatidylcholine alone. Studies with phospholipid monolayers suggest that Tim44 binds to phospholipids of the mitochondrial inner membrane both by electrostatic interactions and by penetrating the polar head group region.

Original languageEnglish
Pages (from-to)8890-8894
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume96
Issue number16
DOIs
StatePublished - 3 Aug 1999

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