The importance of the glycerol 3-phosphate shuttle during aerobic growth of Saccharomyces cerevisiae
Article first published online: 4 DEC 1998
Copyright © 1998 John Wiley & Sons, Ltd.
Volume 14, Issue 4, pages 347–357, 15 March 1998
How to Cite
Larsson, C., Påhlman, I.-L., Ansell, R., Rigoulet, M., Adler, L. and Gustafsson, L. (1998), The importance of the glycerol 3-phosphate shuttle during aerobic growth of Saccharomyces cerevisiae. Yeast, 14: 347–357. doi: 10.1002/(SICI)1097-0061(19980315)14:4<347::AID-YEA226>3.0.CO;2-9
- Issue published online: 4 DEC 1998
- Article first published online: 4 DEC 1998
- Manuscript Accepted: 10 SEP 1997
- Manuscript Received: 14 MAY 1997
- Nordic Industrial Fund. Grant Number: P93 021
- Swedish National Board for Industrial and Technical Development. Grant Numbers: P1009-1, P94-2901
Maintenance of a cytoplasmic redox balance is a necessity for sustained cellular metabolism. Glycerol formation is the only way by which Saccharomyces cerevisiae can maintain this balance under anaerobic conditions. Aerobically, on the other hand, several different redox adjustment mechanisms exist, one of these being the glycerol 3-phosphate (G3P) shuttle. We have studied the importance of this shuttle under aerobic conditions by comparing growth properties and glycerol formation of a wild-type strain with that of gut2Δ mutants, lacking the FAD-dependent glycerol 3-phosphate dehydrogenase, assuming that the consequent blocking of G3P oxidation is forcing the cells to produce glycerol from G3P. To impose different demands on the redox adjustment capability we used various carbon sources having different degrees of reduction.
The results showed that the shuttle was used extensively with reduced substrate such as ethanol, whereas the more oxidized substrates lactate and pyruvate, did not provoke any activity of the shuttle. However, the absence of a functional G3P shuttle did not affect the growth rate or growth yield of the cells, not even during growth on ethanol. Presumably, there must be alternative systems for maintaining a cytoplasmic redox balance, e.g. the so-called external NADH dehydrogenase, located on the outer side of the inner mitochondrial membrane. By comparing the performance of the external NADH dehydrogenase and the G3P shuttle in isolated mitochondria, it was found that the former resulted in high respiratory rates but a comparably low P/O ratio of 1·2, whereas the shuttle gave low rates but a high P/O ratio of 1·7.
Our results also demonstrated that of the two isoforms of NAD-dependent glycerol 3-phosphate dehydrogenase, only the enzyme encoded by GPD1 appeared important for the shuttle, since the enhanced glycerol production that occurs in a gut2Δ strain proved dependent on GPD1 but not on GPD2. © 1998 John Wiley & Sons, Ltd.