The special
interaction of Gut2p with phosphatidylcholine.
Pieter Rijken,
Marjolein Janssen, Toon de Kroon, Ben de Kruijff
Biochemistry of Membranes, Institute of Biomembranes, Padualaan 8, Utrecht,
NL-3584 CH, The Netherlands (p.j.rijken@chem.uu.nl)
Yeast strains with defects in the biosynthesis of phosphatidylcholine (PC) tend to form respiratory-deficient petites at high frequency, suggesting that PC is required for proper mitochondrial function. Changing the PC content may affect barrier properties of the mitochondrial membranes or specific PC-protein interactions. The objectives of our research are (a) to identify such specific PC-protein interactions in yeast mitochondria and (b) to establish the functions of these proteins and whether, and if so how, their functions depend on PC. Recently, Janssen et al. [Biochemistry 41 (2002), 5702-5711] introduced the photoactivatable PC analogue TID-PC in isolated yeast mitochondria to identify such specific interactions. After photoactivation, a number of proteins was found to be crosslinked to TID-PC. The proteins were identified via 2D gel electrophoresis, N-terminal sequencing and mass spectrometry. One of the more efficiently crosslinked proteins was identified as Gut2p, the mitochondrial enzyme FAD-dependent glycerol-3-phosphate dehydrogenase, which is involved in the glycerol-3-phosphate shuttle and is essential for growth on glycerol. Currently, we are investigating the functional significance of the interaction of Gut2p with PC. Using yeast PC biosynthetic mutant strains, the possible dependence of Gut2p activity on the PC content of the cells is investigated.