Isoprenoid synthesis gene for geranylgeranyl diphosphate synthase from a hyperthermophile, Pyrococcus sp. strain OT3

Pyrococcus sp, strain OT3, a hyperthermophilic archaeon that was isolated b y the authors was found to contain tetraether lipid mainly in the membrane lipid, which was quite different from the other hyperthermophiles (Masuchi et al, 1997), Those isoprenoids are synthesized by a family of isoprenyl di phosphate synthases from isopentenyl diphosphate to allylic diphosphates. T he gene that encodes one of these families, geranylgeranyl diphosphate synt hase (GGPPSase), from this strain was cloned and sequenced. This coding gen e has a 960-bp (320aa) sequence. The putative Shine-Dalgarno sequence was s ix bases upper of start codon, exactly the same as Methanobacterium thermoa utotrophicum, a methnogenic thermophile. Comparison of the amino acid seque nce of 13 organisms including Eukarya, Bacteria, and Archaea showed that Ar chaea strains including Pyrococcus sp. strain OT3 consisted of a separate g roup from the others, but five conservative regions are very homologous.