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  • The EMBO Journal (2000) 19, 4383 - 4392
  • doi:10.1093/emboj/19.16.4383

The ATPase cycle of Hsp90 drives a molecular 'clamp' via transient dimerization of the N-terminal domains

Chrisostomos Prodromou1,5, Barry Panaretou1,2,5, Shahzad Chohan3, Giuliano Siligardi4, Ronan O'Brien2, John E. Ladbury2, S.Mark Roe1, Peter W. Piper2 and Laurence H. Pearl1

  1. Section of Structural Biology, Institute of Cancer Research, Chester Beatty Laboratories, 237 Fulham Road, London SW3 6JB, UK
  2. Department of Biochemistry and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
  3. Present address: Department of Biochemistry, Imperial College of Science, Technology and Medicine, Exhibition Road, London SW7 2AZ, UK
  4. Pharmaceutical Optical Spectroscopy Centre, Department of Pharmacy, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 8WA, UK
  5. C.Prodromou and B.Panaretou contributed equally to this work

Correspondence to:

Laurence H. Pearl, E-mail: l.pearl@icr.ac.uk

Received 10 January 2000; Accepted 30 June 2000; Revised 30 June 2000

How the ATPase activity of Heat shock protein 90 (Hsp90) is coupled to client protein activation remains obscure. Using truncation and missense mutants of Hsp90, we analysed the structural implications of its ATPase cycle. C-terminal truncation mutants lacking inherent dimerization displayed reduced ATPase activity, but dimerized in the presence of 5'-adenylamido-diphosphate (AMP-PNP), and AMP-PNP- promoted association of N-termini in intact Hsp90 dimers was demonstrated. Recruitment of p23/Sba1 to C-terminal truncation mutants also required AMP-PNP-dependent dimerization. The temperature- sensitive (ts) mutant T101I had normal ATP affinity but reduced ATPase activity and AMP-PNP-dependent N-terminal association, whereas the ts mutant T22I displayed enhanced ATPase activity and AMP-PNP-dependent N-terminal dimerization, indicating a close correlation between these properties. The locations of these residues suggest that the conformation of the 'lid' segment (residues 100–121) couples ATP binding to N-terminal association. Consistent with this, a mutation designed to favour 'lid' closure (A107N) substantially enhanced ATPase activity and N-terminal dimerization. These data show that Hsp90 has a molecular 'clamp' mechanism, similar to DNA gyrase and MutL, whose opening and closing by transient N-terminal dimerization are directly coupled to the ATPase cycle.

  • Keywords:

    • chaperone,
    • conformational switch,
    • cross-linking,
    • mutational analysis