The Amino Acid Usage Bias Of Orthologous Proteins And Their Ancester Protein Of Bacteria

Proteins in the genome are translated from the nucleotide sequences, so the genome will directly affect the composition of protein amino acids. In order to be proven whether the orthologous protein composition of preferences, to identify orthologous proteins in the nucleotide composition, protein amino acid composition of its functions is still the strict restrictions and informed protein composition of evolution. In this study, the relationship between the amino acid composition of orthologous in 69 bacteria and genomic GC% the content of ,different functional categories of orthologous proteins and amino acid composition of ancestral sequences, the following conclusions:(1) Although the orthologous gene from a common ancestor, in the same function in different species, all of orthologous proteins conserved between the amino acid composition should have, but studies have shown that the amino acid composition of orthologous proteins affect by genome nucleotide composition preferences .(2) The amino acid composition of orthologous proteins not only by gene mutation pressure level decisions, but also protein levels of selection pressure by the decision.(3) Conserved orthologous protein sequences and complete sequences of orthologous proteins between the fundamental frequency of a single amino acid did not differ, but they vary among different species reduced than before.(4) serine (S), valine (V), glutamic acid amide (Q) and glycine (G) in the frequency of ancestral proteins with the existing significant differences in protein, other amino acids did not differ. Extant species in the high frequency of serine (S) and glutamic acid amide (Q), the energy required for their synthesis of amino acids in all is relatively low, the synthesis steps required to have at least, which indicated that the amino acid composition of the direction to the evolution of the energy economical trends.(5) In this study we found that the genetic distance of different species, orthologous proteins have different amino acid composition, genomic GC% species similar to the protein content does not necessarily have similar amino acid composition, and close genetic relationship between species more similar amino acid composition. Can see different species codon preference choice.Orthologous proteins and other proteins, as preferred by the genome of nucleotides, this finding gives us the composition of orthologous proteins have a new understanding. The use of orthologous proteins as a study object, in all species suffered the same protein level of selection pressure, to obtain the true protein composition affecting by composition of the genome. The composition of the protein from the ancestors to explore the evolution of protein composition, than in living species evolved to discuss the composition of the protein is more reliable. The study concluded the selection of species for a variety of materials, bioinformatics analysis provide a reference.