title: Evolution of the vertebrate goose-type lysozyme gene family.
abstract: BACKGROUND
  Lysozyme g is an antibacterial enzyme that was first found in the eggs of some birds, but recently has been found in additional species, including non-vertebrates. Some previously characterized lysozyme g sequences are suggested to have altered secretion potential and enzymatic activity, however the distribution of these altered sequences is unknown. Duplicated copies of the lysozyme g gene exist in some species; however, the origins of the duplicates and their roles in altered function are unclear.
  
  
  RESULTS
  We identified 234 lysozyme g sequences from 118 vertebrate species, including 181 sequences that are full or near full length representing all vertebrate classes except cartilaginous fish. Phylogenetic analysis shows that most lysozyme g gene duplicates are recent or lineage specific events, however three amplification events are more ancient, those in an early amniote, an early mammal, and an early teleost. The older gene duplications are associated with changes in function, including changes in secretion potential and muramidase antibacterial enzymatic activity.
  
  
  CONCLUSIONS
  Lysozyme g is an essential muramidase enzyme that is widespread in vertebrates. Duplication of the lysozyme g gene, and the retention of non-secreted isozymes that have lost enzymatic activity indicate that lysozyme g has an activity other than the muramidase activity associated with being an antibacterial enzyme.
authors.affiliation: Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto M5S 1A8, Ontario, Canada. david.irwin@utoronto.ca.
authors.forename: David M
authors.initials: DM
authors.lastname: Irwin
mesh_terms: D000818:Animals; D001483:Base Sequence; D019143:Evolution, Molecular; D005777:Geese / Q000235:genetics*; D020440:Gene Duplication; D005810:Multigene Family / Q000235:genetics; D009113:Muramidase / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny
chemical_list: D009113:Muramidase