ATPase cycle controls the conformation of an archaeal chaperonin as visualized by cryo-electron microscopy

Chaperonins are double-ring protein folding machines fueled by ATP binding and hydrolysis. Conformational rearrangements upon ATPase cycling of the gr oup I chaperonins, typified by the Escherichia coli GroEL/GroES system, hav e been thoroughly investigated by cryo-electron microscopy and X-ray crysta llography. For archaeal group II chaperonins, however, these methods have s o far failed to provide a correlation between the structural and the functi onal states. Here, we show that the conformation of the native alpha beta-t hermosome of Thermoplasma acidophilum in vitrified ice is strictly regulate d by adenine nucleotides. (C) 2000 Federation of European Biochemical Socie ties. Published by Elsevier Science B.V. All rights reserved.