Studies on the subunit cooperative mechanism in the reaction cycle of group 2 chaperonin

2014 Fiscal Year Final Research Report

• Project/Area Number: 24370064
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Biophysics
• Research Institution: Tokyo University of Agriculture and Technology
• Principal Investigator: YOHDA MASAFUMI 東京農工大学, 工学(系)研究科(研究院), 教授 (50250105)
• Co-Investigator(Kenkyū-buntansha): SEKIGUCHI Hiroshi 公益財団法人高輝度光科学研究センター, 利用研究促進部門, 研究員 (00401563)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: フォールディング / シャペロン / 構造変化機構 / 古細菌

Outline of Final Research Achievements

Group 2 chaperonin (CPN) plays important roles in proteostasis in cytosol of eukaryotes or archaea. The aim of this study is to reveal the detailed protein folding mechanism of CPN. By kinetic analyses using stopped-flow fluorometry and diffracted X-ray tracking, we could dissect the conformational change process of CPN. ATP binding to each subunit causes conformational change and cooperation of subunits in the ring induces transition from open to closed conformation. Then, the ring twisted counterclockwise in ATP hydrolysis manner to induce folding of the protein in the cavity. Subsequently, the ring reverts to the original state by a clockwise twist to release the folded protein. Finally, we have succeeded to construct asymmetric CPN, CPN-ASP, in which one ring is composed of wild type subunits and the other one of mutant subunits. By charactering CPN-ASP, we have shown that the inter-ring communication is dispensable in the reaction cycle of CPN.

Free Research Field

生化学、生物工学、構造生物学