Nitrogen Assimilation Pathways in Budding Yeasts

Abstract

The element nitrogen is an essential macronutrient for all living organisms. Like other microorganisms, budding yeasts (phylum Ascomycota, subphylum Saccharomycotina) have evolved a versatile enzymatic toolbox for the extraction of nitrogen from a wide array of nitrogen-containing compounds. This chapter will review our current knowledge of pathways and enzymes involved in the assimilation of individual categories of nitrogen compounds including ammonia, nitrate, amino acids, amides, amines, purines, pyrimidines as well as aromatic and heterocyclic nitrogen compounds. The genes encoding the corresponding enzymes are listed whenever possible. Since the ability to assimilate specific categories of nitrogen compounds continue to be used for classification of budding yeasts, the taxonomic context of the occurrence of individual pathways and enzymes is emphasized throughout. Current as well as possible future biotechnology applications of budding yeast nitrogen assimilation pathways and enzymes are also discussed.