Sequence comparison of the ARG4 chromosomal regions from the two related yeasts, Saccharomyces cerevisiae and Saccharomyces douglasii.
A 3.6 kb DNA fragment from Saccharomyces douglasii, containing the ARG4 gene, has been cloned, sequenced and compared to the corresponding region from Saccharomyces cerevisiae. The organization of this region is identical in both yeasts. It contains besides the ARG4 gene, another complete open reading frame (ORF) (YSD83) and a third incomplete one (DED81). The ARG4 and the YSD83 coding regions differ from their S. cerevisiae homologs by 8.1% and 12.5%, respectively, of base substitutions. The encoded proteins have evolved differently: amino acid replacements are significantly less frequent in Arg4 (2.8%) than in Ysc83 (12.4%) and most of the changes in Arg4 are conservative, which is not the case for Ysc83. The non-coding regions are less conserved, with small AT-rich insertions/deletions and 20% base substitutions. However, the level of divergence is smaller in the aligned sequences of these regions than in silent sites of the ORFs, probably revealing a higher degree of constraints. The Gcn4 binding site and the region where meiotic double-strand breaks occur, are fully conserved. The data confirm that these two yeasts are evolutionarily closely related and that comparisons of their sequences might reveal conserved protein and DNA domains not expected to be found in sequence comparisons between more diverged organisms.
Institut Curie, Orsay, France.
A
A
Adjiri
R
R
Chanet
C
C
Mezard
F
F
Fabre
D000595:Amino Acid Sequence; D001123:Argininosuccinate Lyase; D001483:Base Sequence; D005075:Biological Evolution; D015825:Chromosomes, Fungal; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004171:Diploidy; D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal / Q000235:genetics*; D008969:Molecular Sequence Data; D016366:Open Reading Frames / Q000235:genetics; D011995:Recombination, Genetic; D012440:Saccharomyces / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity
D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; C087900:Arg4 protein, S cerevisiae; D001123:Argininosuccinate Lyase