ABSTRACT
Prized by humankind for its ability to ferment glucose, the yeast Saccharomyces cerevisiae generates ATP preferentially from substrate level phosphorylation. This chapter describes heme-mediated, posttranscriptional regulation of gene expression in Saccharomyces cerevisiae. Hemoproteins are found in nearly all subcellular compartments in yeast and are encoded by both nuclear and mitochondrial genes. Expression of many of the hemoproteins is regulated by heme. The mitochondrial hemoproteins include cytochromes associated with the electron transport complex, which are located on the inner mitochondrial membrane. Heme is an indicator of carbon source and oxygen availability in yeast cells; strains deficient in heme biosynthesis grown without heme supplementation exhibit the same inability to express respiratory genes as wild-type strains grown anaerobically. Heme-regulated translation also occurs in reticulocyte lysates. Heme is also necessary for the accumulation and assembly of the yeast cytochrome oxidase subunits in S. cerevisiae.
