15. Hemiascomycetous Yeasts

Summary

• The mission of this chapter is 3-fold: (i) it gives an account of the achievements of sequencing and analyzing the genomes of a large variety of yeast species that belong to the Ascomycota and the Basidiomycota, (ii) it summarizes the interesting biological characteristics of a number of yeast species, and (iii) it discusses numerous investigations aimed at an understanding the evolution of regulatory networks by comparative functional genomics.

• The main attention is focused on the Génolevures program, which was initiated at the end of the last century to investigate the genomes of 13 Hemiascomycetous yeast species covering more than 300 million years of evolution. While some species were selected also for their own interest in medicine (C. tropicalis) or biotechnology (e.g., S. uvarum, K. lactis, H. polymorpha (called P. angusta in this project), D. hansenii, and Y. lipolytica), the main objective was to cover as extensively as possible the Hemiascomycete phylogenetic tree. We do not offer a detailed description of the procedures applied for sequencing, annotations, and further analyzes of the data. All endeavors can be judged from the datasets provided by the Génolevures database.

• A complete section is devoted to the “Ecology, Metabolic Specificities, and Scientific Interest of Selected Species.” The reader will find descriptions for a number of yeasts: C. glabrata (a pathogenic cousin of S. cerevisiae), S. kluyveri (an opportunistic anaerobe), K. lactis (a respiro-fermentative yeast), A. gossypii (a filamentous plant pathogen), D. hansenii (an osmotolerant yeast), P. stipitis (a xylose utilizing yeast), P. pastoris (a methanol utilizing yeast), A. adeninivorans (a thermotolerant yeast), and Y. lipolytica (an “oily” yeast).

• The next section offers brief summaries on the differences of architectural features and genetic outfit among these different yeasts: protein families, codon usage, spliceosomal introns, transposons, specific gene arrays, pseudogenes, and noncoding RNAs.

• The final section discusses the insights obtained from various comparative genomic approaches that have contributed to an understanding of the mechanisms underlying the evolution of regulatory networks.