title: Recruitment of lysozyme as a major enzyme in the mouse gut: duplication, divergence, and regulatory evolution.
abstract: Two major types of lysozyme c (M and P) occur in the mouse genus, Mus, and have been purified from an inbred laboratory strain (C58/J) of M. domesticus. They differ in physical, catalytic, and antigenic properties as well as by amino acid replacements at 6 of 49 positions in the amino-terminal sequence. Comparisons with four other mammalian lysozymes c of known sequence suggest that M and P are related by a gene duplication that took place before the divergence of the rat and mouse lineages. M lysozyme is present in most tissues; achieves its highest concentration in the kidney, lung, and spleen; and corresponds to the lysozyme partially sequenced before from another strain of M. domesticus. In M. domesticus and several related species, P lysozyme was detected chiefly in the small intestine, where it is probably produced mainly by Paneth cells. A survey of M and P levels in 22 species of muroid rodents (from Mus and six other genera) of known phylogenetic relationships suggests that a mutation that derepressed the P enzyme arose about 4 million years ago in the ancestor of the housemouse group of species. Additional regulatory shifts affecting M and P levels have taken place along lineages leading to other muroid species. Our survey of 187 individuals of wild house mice and their closest allies reveals a correlation between latitude of origin and level of intestinal lysozyme.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D005075:Biological Evolution; D014644:Genetic Variation; D007421:Intestine, Small / Q000201:enzymology*; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008815:Mice, Inbred Strains; D009113:Muramidase / Q000235:genetics* / Q000378:metabolism; D013045:Species Specificity
chemical_list: D007527:Isoenzymes; D009113:Muramidase