ABSTRACTThe increasing number of genome sequences of archaea and bacteria show their adaptation to different environmental conditions at the genomic level.Aeropyrumspp. are aerobic and hyperthermophilic archaea.Aeropyrum caminiwas isolated from a deep-sea hydrothermal vent, andAeropyrum pernixwas isolated from a coastal solfataric vent. To investigate the adaptation strategy in each habitat, we compared the genomes of the two species. Shared genome features were a small genome size, a high GC content, and a large portion of orthologous genes (86 to 88%). The genomes also showed high synteny. These shared features may have been derived from the small number of mobile genetic elements and the lack of a RecBCD system, a recombinational enzyme complex. In addition, the specialized physiology (aerobic and hyperthermophilic) ofAeropyrumspp. may also contribute to the entire-genome similarity. Despite having stable genomes, interference of synteny occurred with two proviruses,A. pernixspindle-shaped virus 1 (APSV1) andA. pernixovoid virus 1 (APOV1), and clustered regularly interspaced short palindromic repeat (CRISPR) elements. Spacer sequences derived from theA. caminiCRISPR showed significant matches with protospacers of the two proviruses infectingA. pernix, indicating thatA. caminiinteracted with viruses closely related to APSV1 and APOV1. Furthermore, a significant fraction of the nonorthologous genes (41 to 45%) were proviral genes or ORFans probably originating from viruses. Although the genomes ofA. caminiandA. pernixwere conserved, we observed nonsynteny that was attributed primarily to virus-related elements. Our findings indicated that the genomic diversification ofAeropyrumspp. is substantially caused by viruses.
Recognition of tRNA by aminoacyl-tRNA synthetase from hyperthermophilic archaea, Aeropyrum pernix K1
