| The distributions of genes in genomes are not random, which relate with sequence and functions. There are three major levels in the evolutionary process of life, including genes, organisms and species. Each has its role in the process:gene mutated randomly. organisms been selected and species evolving. However, the rapid improvement of sequencing technology boosts the number of whole genomes sequenced species. After analyzing the genomic data, they conclude that 1) variations of the positions are not random; 2) The conservation of genes’sequence are varibality. No one report the relationship between the sequence and position and the experiment of confirmation. In this context, we focus on three key genes trpR, trpE and aroH related with the Tryptophan biosynthetic system to find the relationships of them by the comparative genomic methods, and then, to observe and strength it using molecular biology experiments.First, we find that there are 205 species of whole genome sequenced content at least one of the gene trpR, trpE and aroH according to the taxonomy. And then, we collect genome data including amino acid sequence, position, taxonomic information, oriC region, and the length of genomes. Based on its taxonomic information, we conclude that 189 in 205(92.64%) species belonged to Proteobacteria in Enterobacteriaceae Vibrionaceae and Pasteurellaceae phylum. In the light of the biological background of the data, we calculate the relative distances between the genes and replication start positions and the relative distances D-trpR-trpE, trpR-aroH, the results show that 1) relative distances are concentration and little variability in Enterobacteriaceae and Vibrionaceae, but not in Pasteurellaceae, especially for the D-trpR-trpE; 2) there is significant different of D-trpR-trpE among the three PhylumsNext, we reconstruct three gene trees by the use of its amino acid sequence. After comparing them with species tree, we conclude that 1) the conservation from high to low of the genes is trpE, aroH and trpR; 2) the relative distances and the sequences of most of the species are relative conservable; 3) the sequcence of TrpR change along with D-trpE-trpR in a non-random way in some species including Citrobacter koseri in Enterobacteriaceae, Photobacterium profundum in Vibrionaceae, Pasteurella multocida and Haemophilus parasuis in Pasteurellaceae, except Haemophilus somnus. So we can infer that in the evolutionary process, natural selection persist the fitness variation in the genomes of species. Meanwhile, besides the point mutation, genome rearrangement, recombination and lateral gene transfer help acceleratory shaping the genomic sequence and architecture.To investigate the model of repressor gene tipR together with trp and aroH operons, we replace its original promoter to tet promoter within Escherichia coli MG1655. After cultivated 266 generations in non-trp medium, one base of aroH mutated from Cytosine to Thymine in 910bp. Therefore, we can preliminarily conclude that the mutation results of the promoter change in spite of not adequate of one mutation. But it also can be explain by the weak regulation by lac promoter, so we continue changed the lac to tet promoter and fuse a fluorescent protein gene yfp and cfp behind the trpEDCBA and aroH operon respectively that do not disturbs the origin of the sequence and functions of the trp and aroH operon and of growth of the bacteria. All those efforts laid the foundation of further reconstruct the trpR positon changed strains, tryptophan biosynthesis for checking the positive mutations and how the bacterium adapt the mutations in the dynamic evolutionary process. |
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