• Applied Microscopy
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• v.30 no.4
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• pp.413-421
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• 2000

We have isolated a large cylindrical protein complex from hyperthermophile archaeon Thermococcus profundus. Structural analysis by image processing of electron micrographs suggests that the complex is composed of two stacked rings of eight subunits each; the ring enclose a central channel. The purified protein was shown to be a homomultimer of 60 kDa subunit (P60 complex). It exhibits an extremely thermostable ATPase activity with a temperature optimum of $80^{\circ}C$. This protein complex may play an important role in the adaptation of thermophile archaeon to life at high temperature.