Analysis Of Mechanism Of Thermophiles Thermo-stability And Thermo-adaptation

Life on earth shows a strong ability to adapt to environment. It is known that most organisms live in the temperature between 20℃～50℃, while certain microorganism can grow above 50℃, and others below 20℃. Organisms grow above+46℃are defined as thermophiles. The mechanism of thermo-adaptation has always been of great concern. Thanks to the rapid progress in bioinformatics and the accumulation of genomic data, we can investigate the thermo-stability and thermo-adaptation of the thermophilics from the perspective of genomics and proteomics.Previous researches in the thermophilic mechanism of the thermophiles mainly focused on the sequences or structures of a certain protein family. Up to now, it has accumulated a large number of microbial genomic data. Therefore, we decided to make a comprehensive analysis from the view of whole genomics and proteomics, in order to reveal the relation between protein properties and thermo-adaptation, as well as the protein function evolution. Firstly, we chose the proteomic data from 526 eubacteria and archaeal. By using reciprocal-BLAST, we identified all of the orthologs from the 526 prokaryotics, and analyzed the thermo-adaptation mechanism from the protein sequence level. The results showed an amino acid usage bias. The COG analysis showed that more functional proteins from hyper-/thermophiles were involved in 'information storage and processing'. Finally we investigated the structures of these proteins.Furthermore, the relations between amino acid stability and thermo-adaptation were investigated. Through analyzing the correlations between amino acid content and optimal growth temperature (OGT) for 297 prokaryotic genomes, the relationship between amino acid stability and thermophilic adaptation is fully addressed. Besides the stability of DNA and protein, amino acid stability is also a determinant of thermophilic adaptation. The present finding not only provides further evidence to support the effectiveness of IVYWREL in predicting prokaryotic OGTs, but also implies that amino acid stability plays a causative role in the selection of this amino acid set in thermophiles, which was further demonstrated by analyzing the amino acid content of Top-90 orthologs.