ATP-triggered ADP release from the asymmetric chaperonin GroEL/GroES/ADP(7) is not the rate-limiting step of the GroEL/GroES reaction cycle

作者：Tyagi Navneet K; Fenton Wayne A; Horwich Arthur L^*

来源：FEBS Letters, 2010, 584(5): 951-953.

DOI：10.1016/j.febslet.2010.01.021

• GroEL
• GroES
• ATP
• ADP
• Nucleotide cycle
• Coupled enzyme assay

The GroEL/GroES protein folding chamber is formed and dissociated by ATP binding and hydrolysis. ATP hydrolysis in the GroES-bound (cis) ring gates entry of ATP into the opposite unoccupied trans ring, which allosterically ejects cis ligands. While earlier studies suggested that hydrolysis of cis ATP is the rate-limiting step of the cycle (t(1/2) similar to 10 s), a recent study suggested that ADP release from the cis ring may be rate-limiting (t(1/2) similar to 15-20 s). Here we have measured ADP release using a coupled enzyme assay and observed a t(1/2) for release of <= 4-5 s, indicating that this is not the rate-limiting step of the reaction cycle.

• 出版日期2010-3-5