S-adenosyl-l-methionine (SAM) is an important molecule in the cellular
metabolism of
mammals. In this study, we examined several of the physiological characteristics of a SAM-accumulating
strain of the
yeast Scheffersomyces stipitis (M12), including SAM
production,
ergosterol content, and
ethanol tolerance. S. stipitis M12 accumulated up to 52.48 mg SAM/g dry
cell weight.
Proteome analyses showed that the disruption of C-24
methylation in
ergosterol biosynthesis, a step mediated by C-24
sterol methyltransferase (Erg6p), results in SAM accumulation by S. stipitis M12 compared to the wild-type
strain. A comparative
proteome-wide
analysis identified 25
proteins that were differentially expressed by S. stipitis M12. These
proteins are involved in
ribosome biogenesis, translation, the stress response,
ubiquitin-dependent catabolic processes, the
cell cycle,
ethanol tolerance,
posttranslational modification, peroxisomal
membrane stability,
epigenetic regulation, the
actin cytoskeleton and
cell morphology,
iron and
copper homeostasis,
cell signaling, and
energy metabolism (AU)