The archaea of the genera Pyrococcus belong to the Thermococcales order those of the Thermococcales order are hyperthermophiles, strictly anaerobes and obligate heterotrophs. Complete genome sequences are now available for three species of the Pyrococcus genus: P. Here we present the results of comparisons of the genomic sequences of the archaea Pyrococcus performed to elucidate the possible mechanisms of archaeal adaptation to life under different abiotic and biotic environmental conditions.
High throughputs would allow to uncover the yet unclear molecular mechanisms of the adaptation of prokaryotes to challenging and/or novel environments at the level of genomic organization and protein structure. Complete genomic sequences of the prokaryotes give valuable information about the composition of genes, their function, arrangement order in the genome, operon structure, about single nucleotide substitutions in the coding and noncoding parts of the gene as well. In the postgenomic era, comparative genomics keeps providing powerful tools for unraveling the molecular mechanisms of microbial adaptation. Microbial diversity is not only an academic issue, "it is a treasure house of innovation for the biotechnology industries". It is becoming increasingly apparent that the deep seas are the sources of novel microbial communities and of their so far unclear adaptive abilities. It is remarkable how the prokaryotes manage to survive and proliferate in the habitats exposed to an enormous spectrum of conditions despite their simplest organization. abyssi showed that the fixation rate was higher for radical substitutions relative to the volume of amino acid side-chain. Analysis of radical amino acid replacement rate in evolving P. abyssi was related with positive selection for the genes mainly involved in inorganic ion transport. horikoshii divergence, positive selection was found to operate mainly on the transcription machinery divergence of P. furiosus archaea might have been due to loss of some genes involved in cell motility or signal transduction, and/or to evolution under positive selection of the genes for translation machinery. It was demonstrated that the function of genes that have been subject to positive Darwinian selection is closely related to abiotic and biotic conditions to which archaea managed to become adapted. abyssi might have occurred from ancestral deep-sea organisms. Phylogenetic analysis of rRNA genes from 26 Pyrococcus strains suggested that the divergence of P.
0 kommentar(er)
