Yeast Genetics and Molecular Biology 2000
University of Washington
Seattle, Washington USA
July 2000

Name: Dujon, Bernard
Mailing Address: Genet.Moleculaire des Levures, Institut Pasteur, 25 rue Docteur Roux, Paris, F75724, France
Email Address: bdujon@pasteur.fr
Phone & FAX numbers: 33 1 45 68 84 82 & 33 1 40 61 3456

#049

Systematic comparative genomics within the hemiascomycete phylum reveals mechanisms of eukaryotic genome evolution.
Bernard Dujon (1), Alain Malpertuy (1), Bertrand Llorente (1), Gaelle Blandin (1), Fredj Tekaia (1), Jean Luc Souciet (2), Jean Weissenbach (3)
(1) Genet. Moleculaire des Levures, Institut Pasteur, 25 rue Docteur Roux, Paris, F75724, France; (2) Institut de Botanique, Univ. Louis Pasteur, 28 rue Goethe, Strasbourg-Cedex, France; (3) Genoscope-Centre National de Séquençage, 2 rue Gaston Crémieux BP191, F-91006 Evry-Cedex, France

A comprehensive comparative sequencing program was performed on 13 different yeast species with increasing phylogenetic distances from S. cerevisiae. Approximately 50,000 sequences (totalling ca. 50 megabases) from 3-5 kb long random genomic fragments were analyzed by comparison to S.cerevisiae and all other completely sequenced organisms. A total of ca. 20,000 novel yeast genes were partially or totally sequenced. This analysis - the first performed on a such a scale across the spectrum of a single eukaryotic phylum - reveals the relative importance of sequence divergence, gene loss/acquisition and chromosomal rearrangements in the evolution of eukaryotic genomes. Interestingly, a significant number of yeast genes appears as 'ascomycete-specific'. Some of them are functionally characterized in S. cerevisiae. From the analysis of synteny and gene orientation across the hemiascomycete realm, we suggest a model for molecular evolution which emphasizes the role of continuous duplicative transpositions of chromosome segments, each encompassing several genes, equilibrated by the continuous deletion of single genes. The extent of the phenomenon is such that the number of duplication-loss events may equal the total number of genes during an evolutionary period like the one separating S. cerevisiae from Yarrowia lipolytica or Candida tropicalis. Gene families and comparative functional classifications from the same set of data will be presented separately (Gaillardin et al.).

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