Molecular Evolutionary Analysis Of Metallothionein Gene

Metallothionein is a protein with important biological functions, called MT for abbreviation. So far, the amino acid sequences of metallothionein discovered and identified are more than 200. Metallothioneins are generally composed of 61-68 amino acids in length, contain 20 conserved cysteine residues, and can be effectively combined with zinc and other heavy metals, with important biological functions, including maintaining metabolic balance, heavy metal detoxification, cell proliferation and apoptosis, and stress response in scavenging free radicals.The coding sequence and the amino acid sequence of metallothionein contain a large amount of biological information. Focusing too much on metallothionein structure and functions, traditional research neglected that gene sequence , metabolic pathway and regulatory network play a decisive role in the structure and function research. With these sequences contained a lot of biological information, digging out the important biological knowledge is beneficial for further study in providing reference and guidance.In this study, the data of metallothionein coding sequence and amino acid sequence were collected to construct phylogenetic tree. By bayesian method. And phylogenetic tree, the metallothionein gene was divided into five subfamilies, using frequency statistics of every subfamily amino acid and the selection pressure analysis found the conserved locus with important bio-function and the selection in the process of evolution.Mammalian metallothionein gene phylogenetic tree was constructed using mammals metallothionein amino acid sequences through neighbor joining method. While mammalian metallothionein gene was analysised in selection pressure and functional differences to detect the positive selection. Mammals metallothionein genes mainly are subject to purifying selection and neutral selection, and they have been or are going through positive selection in their evolution. Some amino acid sites also were detected which may be subject to positive selection.These amino acid sites on mammalian metallothionein gene may have an important role in the function differences.The study provides an important reference for further explore the mammalian metallothionein gene different function and important amino acids locus,easy to further study its structure and function.In this study, phylogenetic trees were constructed through the coding sequence and amino acid sequence of metallothionein, as a whole ,we could further understand of the metallothionein gene in evolutionary history. Analysis of metallothionein gene and functional differences in selection pressure help us have further research on its structure and function so as to understand more about biological characteristics of metallothionein. It is also beneficial for animal nutrition, animal raising, anti-stress and transgenic animal research and use, as well as for human disease research and treatment.