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  • The EMBO Journal (2003) 22, 3557 - 3567
  • doi:10.1093/emboj/cdg349

The molecular chaperone Hsp90 plays a role in the assembly and maintenance of the 26S proteasome

Jun Imai1,2,3, Mikako Maruya2,3, Hideki Yashiroda1,3, Ichiro Yahara3,4 and Keiji Tanaka1,3

  1. Department of Molecular Oncology, Tokyo Metropolitan Institute of Medical Science, Honkomagome 3-18-22, Bunkyo-ku, Tokyo 113-8613, Japan
  2. Department of Cell Biology, Tokyo Metropolitan Institute of Medical Science, Honkomagome 3-18-22, Bunkyo-ku, Tokyo 113-8613, Japan
  3. CREST, Japan Science and Technology Corporation, Honmachi 4-1-8, Kawaguchi, Saitama 332-0012, Japan
  4. Ina Laboratory, Medical and Biological Laboratories Co. Ltd, 1063-103 Ohara Terasawaoka, Ina, Nagano 396-0002, Japan

Correspondence to:

Keiji Tanaka, E-mail: tanakak@rinshoken.or.jp

Received 20 January 2003; Accepted 21 May 2003; Revised 20 May 2003

Hsp90 has a diverse array of cellular roles including protein folding, stress response and signal transduction. Herein we report a novel function for Hsp90 in the ATP-dependent assembly of the 26S proteasome. Functional loss of Hsp90 using a temperature-sensitive mutant in yeast caused dissociation of the 26S proteasome. Conversely, these dissociated constituents reassembled in Hsp90-dependent fashion both in vivo and in vitro; the process required ATP-hydrolysis and was suppressed by the Hsp90 inhibitor geldanamycin. We also found genetic interactions between Hsp90 and several proteasomal Rpn (Regulatory particle non-ATPase subunit) genes, emphasizing the importance of Hsp90 to the integrity of the 26S proteasome. Our results indicate that Hsp90 interacts with the 26S proteasome and plays a principal role in the assembly and maintenance of the 26S proteasome.

  • Keywords:

    • assembly,
    • Hsp90,
    • maintenance,
    • 26S proteasome,
    • yeast