Genomic organization and evolution of ruminant lysozyme c genes.
Ruminant stomach lysozyme is a long established model of adaptive gene evolution. Evolution of stomach lysozyme function required changes in the site of expression of the lysozyme c gene and changes in the enzymatic properties of the enzyme. In ruminant mammals, these changes were associated with a change in the size of the lysozyme c gene family. The recent release of near complete genome sequences from several ruminant species allows a more complete examination of the evolution and diversification of the lysozyme c gene family. Here we characterize the size of the lysozyme c gene family in extant ruminants and demonstrate that their pecoran ruminant ancestor had a family of at least 10 lysozyme c genes, which included at least two pseudogenes. Evolutionary analysis of the ruminant lysozyme c gene sequences demonstrate that each of the four exons of the lysozyme c gene has a unique evolutionary history, indicating that they participated independently in concerted evolution. These analyses also show that episodic changes in the evolutionary constraints on the protein sequences occurred, with lysozyme c genes expressed in the abomasum of the stomach of extant ruminant species showing the greatest levels of selective constraints.
Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada; Banting and Best Diabetes Centre, University of Toronto, Toronto, Canada. david.irwin@utoronto.ca.
David M
DM
Irwin
D000595:Amino Acid Sequence; D000818:Animals; D005075:Biological Evolution; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D016678:Genome; D023281:Genomics; D008969:Molecular Sequence Data; D009113:Muramidase / Q000235:genetics / Q000378:metabolism*; D012418:Ruminants / Q000235:genetics / Q000378:metabolism*
D009113:Muramidase
Concerted evolution; Gene duplication; Gene family; Lysozyme c; Mosaic evolution; Ruminants