ATP‐triggered ADP release from the asymmetric chaperonin GroEL/GroES/ADP7 is not the rate‐limiting step of the GroEL/GroES reaction cycle

• Published in: FEBS letters Vol. 584; no. 5; pp. 951 - 953
• Main Authors: Tyagi, Navneet K., Fenton, Wayne A., Horwich, Arthur L.
• Format: Journal Article
• Language: English
• Published: England 05.03.2010
• Subjects: Adenosine Diphosphate - metabolism; Adenosine Triphosphate - metabolism; ADP; ATP; Chaperonin 10 - genetics; Chaperonin 10 - metabolism; Chaperonin 60 - genetics; Chaperonin 60 - metabolism; Chaperonins - genetics; Chaperonins - metabolism; Coupled enzyme assay; dithiothreitol; DTT; GroEL; GroES; HEPES; Hydrolysis; lactate dehydrogenase; LDH; Models, Biological; N-(2-hydroxyethyl)piperazine-N′-(2-ethanesulfonic acid); Nucleotide cycle; PEP; phosphoenol pyruvate; Protein Binding; Protein Folding; pyruvate kinase
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/j.febslet.2010.01.021

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 ½ ∼ 10 s), a recent study suggested that ADP release from the cis ring may be rate‐limiting (t ½ ∼ 15–20 s). Here we have measured ADP release using a coupled enzyme assay and observed a t ½ for release of ⩽4–5 s, indicating that this is not the rate‐limiting step of the reaction cycle.