Cloning, sequencing and expression of VAT, a CDC48/p97 ATPase homologue from the archaeon Thermoplasma acidophilum

A member of the AAA family of Mg2+-ATPases from the archaeon Thermoplasma acidophilum has been cloned and expressed in Escherichia coli. The protein, VCP-like ATPase of Thermoplasma acidophilum (VAT), is a homologue of SAV from Sulfolobus acidocaldarius and CdcH of Halobacterium salinarium, and belongs to the CDC48/VCP/p97 subfamily. The deduced product of the vat gene is 745 residues long (M(r) 83 000), which has an optimal Mg2+-ATPase activity at 70 degrees C. Electron microscopy shows the purified protein to form single and double homo-hexameric rings, Although the symmetry is different, the appearance of the complexes formed of two rings resembles the 20S proteasome and Hsp60/GroEL. (C) 1997 Federation of European Biochemical Societies.