한빛사 논문
Abstract
Soyeon Park1,2*, Xueming Li3*, Ho Min Kim3†*, Chingakham Ranjit Singh4, Geng Tian1, Martin A. Hoyt5, Scott Lovell6, Kevin P. Battaile7, Michal Zolkiewski8, Philip Coffino5, Jeroen Roelofs4, Yifan Cheng3 & Daniel Finley1
1Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, USA. 2MCD Biology, University of Colorado Boulder, Boulder, Colorado 80309, USA. 3The W.M. Keck Advanced Microscopy Laboratory, Department of Biochemistry and Biophysics, University of California San Francisco, 600 16th Street, San Francisco, California 94158, USA. 4Division of Biology,Kansas State University, 338 Ackert Hall, Manhattan, Kansas 66506, USA. 5Department of Microbiology and Immunology, University of California San Francisco, 513 Parnassus Avenue, San Francisco, California 94143, USA. 6Protein Structure Laboratory, Del Shankel Structural Biology Center, University of Kansas, Lawrence, Kansas 66047, USA. 7IMCA-CAT Hauptman-Woodward Medical Research Institute, 9700 South Cass Avenue, Building 435A, Argonne, Illinois 60439, USA. 8 Department of Biochemistry, Kansas State University, 176 Chalmers Hall, Manhattan, Kansas 66506, USA. †Present address: Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea.
*These authors contributed equally to this work.
Correspondence to: Jeroen Roelofs or Yifan Cheng or Daniel Finley
The proteasomal ATPase ring, comprising Rpt1-Rpt6, associates with the heptameric α-ring of the proteasome core particle (CP) in the mature proteasome, with the Rpt carboxy-terminal tails inserting into pockets of the α-ring1, 2, 3, 4. Rpt ring assembly is mediated by four chaperones, each binding a distinct Rpt subunit5, 6, 7, 8, 9, 10. Here we report that the base subassembly of the Saccharomyces cerevisiae proteasome, which includes the Rpt ring, forms a high-affinity complex with the CP. This complex is subject to active dissociation by the chaperones Hsm3, Nas6 and Rpn14. Chaperone-mediated dissociation was abrogated by a non-hydrolysable ATP analogue, indicating that chaperone action is coupled to nucleotide hydrolysis by the Rpt ring. Unexpectedly, synthetic Rpt tail peptides bound α-pockets with poor specificity, except for Rpt6, which uniquely bound the α2/α3-pocket. Although the Rpt6 tail is not visualized within an α-pocket in mature proteasomes2, 3, 4, it inserts into the α2/α3-pocket in the base-CP complex and is important for complex formation. Thus, the Rpt-CP interface is reconfigured when the lid complex joins the nascent proteasome to form the mature holoenzyme.
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