title: Tempo and mode of Ty element evolution in Saccharomyces cerevisiae.
abstract: The Saccharomyces cerevisiae genome contains five families of long terminal repeat (LTR) retrotransposons, Ty1-Ty5. The sequencing of the S. cerevisiae genome provides an unprecedented opportunity to examine the patterns of molecular variation existing among the entire genomic complement of Ty retrotransposons. We report the results of an analysis of the nucleotide and amino acid sequence variation within and between the five Ty element families of the S. cerevisiae genome. Our results indicate that individual Ty element families tend to be highly homogenous in both sequence and size variation. Comparisons of within-element 5' and 3' LTR sequences indicate that the vast majority of Ty elements have recently transposed. Furthermore, intrafamily Ty sequence comparisons reveal the action of negative selection on Ty element coding sequences. These results taken together suggest that there is a high level of genomic turnover of S. cerevisiae Ty elements, which is presumably in response to selective pressure to escape host-mediated repression and elimination mechanisms.
authors: Department of Genetics, University of Georgia, Athens, Georgia 30602-7223, USA. king@parvati.lv-whi.nevada.edu
authors: I K
authors: IK
authors: Jordan
authors: J F
authors: JF
authors: McDonald
mesh_terms: D000595:Amino Acid Sequence; D019143:Evolution, Molecular; D005656:Fungal Proteins / Q000235:genetics; D005785:Gene Conversion; D014644:Genetic Variation; D016681:Genome, Fungal; D008969:Molecular Sequence Data; D011995:Recombination, Genetic; D018626:Retroelements; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D012641:Selection, Genetic; D017386:Sequence Homology, Amino Acid
chemical_list: D005656:Fungal Proteins; D018626:Retroelements; C094737:p1 protein, yeast