Characterization of the cow stomach lysozyme genes: Repetitive DNA and concerted evolution |
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Authors: | David M. Irwin R. Tyler White Allan C. Wilson |
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Affiliation: | (1) Division of Biochemistry and Molecular Biology, University of California, 94720 Berkeley, CA, USA;(2) Present address: Department of Clinical Biochemistry, University of Toronto, 100 College St., M5G 1L5 Toronto, Ontario, Canada;(3) Present address: California Biotechnology Inc., 2450 Bayshore Parkway, 94043 Mountain View, CA |
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Abstract: | Cow stomach lysozyme genes have evolved in a mosaic pattern. The majority of the intronic and flanking sequences show an amount of sequence difference consistent with divergent evolution since duplication of the genes 40–50 million years ago. In contrast, exons 1, 2, and 4 and immediately adjacent intronic sequences differ little between genes and show evidence of recent concerted evolution. Exon 3 appears to be evolving divergently. The three characterized genes vary from 5.6 to 7.9 kilobases in length. Different distributions of repetitive DNA are found in each gene, which accounts for the majority of length differences between genes. The different distributions of repetitive DNA in each gene suggest the repetitive elements were inserted into each gene after the duplications that give rise to these three genes and provide additional support for divergent evolution for the majority of each gene. The observation that intronic and flanking sequences are evolving divergently suggests that the concerted evolution events involved in homogenizing the coding regions of lysozyme genes involve only one exon at a time. This model of concerted evolution would allow the shuffling of exon-sized pieces of information between genes, a phenomenon that may have aided in the early adaptive evolution of stomach lysozyme.Deceased July 21, 1991Correspondence to: D.M. Irwin |
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Keywords: | Genomic cloning DNA sequencing Multigene family S1 mapping Promoter region Gene expression Concerted evolution Repetitive DNA |
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