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AAA ATPases regulate membrane association of yeast oxysterol binding proteins and sterol metabolism

Penghua Wang1, Yong Zhang, Hongzhe Li

  • 1Department of Biochemistry, Faculty of Medicine, National University of Singapore, Singapore, Singapore.

The EMBO Journal
|August 13, 2005
PubMed

Insights

Yeast oxysterol-binding proteins Osh6p and Osh7p interact with AAA ATPase Vps4p, impacting lipid transport. This interaction, regulated by ergosterol, suggests a shared mechanism for AAA proteins in controlling yeast lipid dynamics.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • The yeast genome contains seven oxysterol-binding protein (OSBP) homologs (Osh1p-Osh7p) involved in intracellular lipid and vesicular transport.
  • AAA ATPases are crucial for various cellular processes, including protein degradation and membrane trafficking.

Purpose of the Study:

  • To investigate the interaction between yeast OSBP proteins (Osh6p and Osh7p) and the AAA ATPase Vps4p.
  • To elucidate the functional consequences of this interaction on lipid transport and cellular processes.

Main Methods:

  • Yeast two-hybrid screening to identify protein-protein interactions.
  • Ergosterol manipulation to study regulatory effects.
  • Gene deletion and overexpression studies.
  • Analysis of protein membrane association and sterol esterification.

Main Results:

  • Osh6p and Osh7p were found to interact with Vps4p, an AAA ATPase.
  • The Osh7p-Vps4p interaction is regulated by ergosterol.
  • VPS4 deletion increased membrane-associated Osh6p and Osh7p and decreased sterol esterification.
  • Overexpression of Osh7p coiled-coil domain (Osh7pCC) caused multivesicular body sorting defects, suggesting Vps4p inhibition.

Conclusions:

  • AAA proteins may share a common mechanism for regulating the membrane association of yeast OSBP proteins.
  • Osh proteins and AAA proteins likely function together to regulate subcellular lipid transport.
  • The interaction between Osh7p and Vps4p plays a role in sterol homeostasis and vesicular trafficking.

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