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A matrix ATP requirement for presequence translocation across the inner membrane of mitochondria

D M Cyr1, R A Stuart, W Neupert

  • 1Institut für Physiologische Chemie, Universität München, Germany.

The Journal of Biological Chemistry
|November 15, 1993
PubMed

Insights

Matrix ATP is crucial for unidirectional protein import into mitochondria. Insufficient ATP levels cause reversible presequence translocation, highlighting the role of matrix ATP and mitochondrial heat shock protein 70 in this process.

Area of Science:

  • Mitochondrial biology
  • Protein import mechanisms
  • Cellular energetics

Background:

  • Mitochondrial protein import is essential for cellular function.
  • The mitochondrial inner membrane potential (delta psi) drives protein translocation.
  • The role of matrix ATP in this process has been less understood.

Purpose of the Study:

  • To investigate the role of matrix ATP in mitochondrial presequence translocation.
  • To elucidate the interplay between delta psi, matrix ATP, and mitochondrial heat shock protein 70 (mthsp70).

Main Methods:

  • Experimental manipulation of matrix ATP levels.
  • Assessing presequence translocation across the inner mitochondrial membrane.
  • Protease accessibility assays to monitor import intermediates.

Main Results:

  • Reduced matrix ATP inhibited presequence translocation, dependent on mthsp70 function.
  • An unprocessed import intermediate accumulated upon ATP depletion.
  • Both delta psi and matrix ATP were necessary for complete translocation into the matrix.

Conclusions:

  • Mitochondrial presequence translocation is reversible without sufficient matrix ATP.
  • Matrix ATP is required to establish a unidirectional import step.
  • A model is proposed involving delta psi, mthsp70, and matrix ATP in regulating mitochondrial protein import.

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