Related Experiment Videos
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.
Insights
Mouse lysozyme c exists in two forms, M and P, differing in function and genetics. A mutation approximately four million years ago likely led to the P form
Area of Science:
- Biochemistry
- Evolutionary Biology
- Genetics
Background:
- Two major types of lysozyme c, M and P, are found in the mouse genus, Mus.
- These lysozymes exhibit distinct physical, catalytic, and antigenic properties.
- Sequence comparisons suggest M and P arose from a gene duplication event predating rat and mouse lineage divergence.
Purpose of the Study:
- To investigate the evolutionary origins and tissue-specific expression of mouse lysozyme c (M and P) types.
- To determine the phylogenetic distribution and regulatory evolution of these lysozymes in muroid rodents.
- To explore potential correlations between lysozyme levels and geographic origin in wild house mice.
Main Methods:
- Purification and characterization of M and P lysozymes from M. domesticus.
- Amino-terminal sequencing and comparison with other mammalian lysozymes.
- Survey of M and P lysozyme levels across 22 muroid rodent species and 187 wild house mice.
Main Results:
- M lysozyme is widely distributed in tissues, with highest concentrations in kidney, lung, and spleen.
- P lysozyme is primarily found in the small intestine, likely produced by Paneth cells.
- A mutation derepressing P lysozyme occurred ~4 million years ago in the ancestor of the house mouse lineage; further regulatory shifts observed in other muroid species.
- A correlation exists between latitude of origin and intestinal lysozyme levels in wild house mice.
Conclusions:
- The M and P lysozyme c types in mice originated from a gene duplication event.
- The P lysozyme likely acquired a new regulatory pattern in the house mouse lineage, with subsequent evolutionary modifications in related species.
- Geographic factors may influence lysozyme expression levels in wild populations.