Re-annotation of two hyperthermophilic archaea Pyrococcus abyssi GE5 and Pyrococcus furiosus DSM 3638.

Pyrococcus abyssi GE5 (P. aby) and Pyrococcus furiosus DSM 3638 (P. fur) are two model hyperthermophilic archaea. However, their annotations in public databases are unsatisfactory. In this article, the two genomes were re-annotated according to the following steps. (i) All "hypothetical genes" in the original annotation were re-identified based on the Z-curve method, and some of them were recognized as non-coding open reading frames (ORFs). Evidence showed that the recognized non-coding ORFs were highly unlikely to encode proteins. (ii) The translation initiation sites (TISs) of all the annotated genes were re-located, and more than 10% of the TISs were shifted to 5'-upstream or 3'-downstream regions. (iii) The functions of the refined "hypothetical genes" were predicted using sequence alignment tools, more than 200 originally annotated "hypothetical genes" in either of the two hyperthermophiles were assigned functions. A large number of these functions have reference support or experimentally characterized homologues. All the refined information will serve as a valuable resource for research on P. aby and P. fur, which may be helpful in the exploration of thermal adaptation mechanisms. The complete re-annotation files of P. aby and P. fur are available at http://211.69.128.148/download/ .