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J. Biol. Chem., Vol. 283, Issue 35, 23774-23781, August 29, 2008

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Revisiting the GroEL-GroES Reaction Cycle via the Symmetric Intermediate Implied by Novel Aspects of the GroEL(D398A) Mutant^*

Ayumi Koike-Takeshita¹, Masasuke Yoshida, and Hideki Taguchi²

From the Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8562, Japan and the Chemical Resources Laboratory, Tokyo Institute of Technology, Midori-ku, Yokohama 226-8503, Japan

The Escherichia coli chaperonin GroEL is a double-ring chaperone that assists in protein folding with the aid of GroES and ATP. It is believed that GroEL alternates the folding-active rings and that the substrate protein (and GroES) can bind to the open trans-ring only after ATP in the cis-ring is hydrolyzed. However, we found that a substrate protein prebound to the trans-ring remained bound during the first ATP cycle, and this substrate was assisted by GroEL-GroES when the second cycle began. Moreover, a slow ATP-hydrolyzing GroEL mutant (D398A) in the ATP-bound form bound a substrate protein and GroES to the trans-ring. The apparent discrepancy with the results from an earlier study (Rye, H. S., Roseman, A. M., Chen, S., Furtak, K., Fenton, W. A., Saibil, H. R., and Horwich, A. L. (1999) Cell 97, 325–338) can be explained by the previously unnoticed fact that the ATP-bound form of the D398A mutant exists as a symmetric 1:2 GroEL-GroES complex (the "football"-shaped complex) and that the substrate protein (and GroES) in the medium is incorporated into the complex only after the slow turnover. In light of these results, the current model of the GroEL-GroES reaction cycle via the asymmetric 1:1 GroEL-GroES complex deserves reexamination.

Received for publication, April 2, 2008 , and in revised form, June 12, 2008.

^* This work was supported by Grant-in-aids for Scientific Research on Priority Areas 17049009, 19037007, and 19058002 (to H. T.) from the Ministry of Education, Culture, Sports, Science, and Technology (MEXT), Japan. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

This article was selected as a Paper of the Week.

¹ Present address: Dept. of Applied Chemistry, Kanagawa Inst. of Technology, 1030 Shimo-ogino, Atsugi, Kanagawa 243-0292, Japan.

² To whom correspondence should be addressed: Dept. of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, FSB401, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan. Fax: 81-4-7136-3644; E-mail: taguchi{at}k.u-tokyo.ac.jp.

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