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Ups1p and Ups2p antagonistically regulate cardiolipin metabolism in mitochondria

Yasushi Tamura1, Toshiya Endo, Miho Iijima

  • 1Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.

The Journal of Cell Biology
|June 10, 2009
PubMed

Insights

Two proteins, Ups1p and Ups2p, regulate cardiolipin levels and mitochondrial protein import. Loss of Ups1p impairs import, but Ups2p loss rescues these defects, revealing a novel cardiolipin metabolism mechanism.

Area of Science:

  • Mitochondrial biology
  • Cellular metabolism
  • Protein import machinery

Background:

  • Cardiolipin is a vital phospholipid in the mitochondrial inner membrane.
  • It is essential for the function of protein complexes like the TIM23 translocase.
  • TIM23 mediates protein import into mitochondria via the presequence translocase-associated motor (PAM).

Purpose of the Study:

  • To investigate the roles of intermembrane space proteins Ups1p and Ups2p in cardiolipin metabolism.
  • To determine how Ups1p and Ups2p affect the TIM23 translocase complex and its association with PAM.
  • To elucidate the mechanism regulating cardiolipin metabolism and mitochondrial protein import.

Main Methods:

  • Analysis of cardiolipin levels in yeast mitochondria.
  • Assessment of TIM23 translocase assembly and its interaction with PAM.
  • Genetic analysis of ups mutants, including double mutants with pam17Delta.

Main Results:

  • Ups1p and Ups2p oppositely regulate cardiolipin metabolism and TIM23/PAM association.
  • Mitochondria lacking Ups1p exhibit reduced cardiolipin, altered TIM23, and impaired protein import.
  • Loss of Ups2p rescues cardiolipin levels and TIM23 defects in ups1Delta mitochondria.
  • Synthetic growth defects observed in ups mutants combined with loss of Pam17p.

Conclusions:

  • Ups1p and Ups2p provide a novel regulatory mechanism for cardiolipin metabolism.
  • These proteins influence mitochondrial protein import by modulating TIM23 complex integrity.
  • The findings offer new insights into the interplay between cardiolipin, protein import, and mitochondrial function.

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