title: Chaperonin-facilitated refolding of ribulosebisphosphate carboxylase and ATP hydrolysis by chaperonin 60 (groEL) are K+ dependent.
abstract: Both the chaperonin- and MgATP-dependent reconstitution of unfolded ribulosebisphosphate carboxylase (Rubisco) and the uncoupled ATPase activity of chaperonin 60 (groEL) require ionic potassium. The spontaneous, chaperonin-independent reconstitution of Rubisco, observed at 15 but not at 25 degrees C, requires no K+ and is actually inhibited by chaperonin 60, with which the unfolded or partly folded Rubisco forms a stable binary complex. The chaperonin-dependent reconstitution of Rubisco involves the formation of a complex between chaperonin 60 and chaperonin 10 (groES). Formation of this complex almost completely inhibits the uncoupled ATPase activity of chaperonin 60. Furthermore, although the formation of the chaperonin 60-chaperonin 10 complex requires the presence of MgATP, hydrolysis of ATP may not be required, since complex formation occurs in the absence of K+. The interaction of chaperonin 60 with unfolded or partly folded Rubisco does not require MgATP, K+, or chaperonin 10. However, discharge of the complex of chaperonin 60-Rubisco, which leads to the formation of active Rubisco dimers, requires chaperonin 10 and a coupled, K(+)-dependent hydrolysis of ATP. We propose that a role of chaperonin 10 is to couple the K(+)-dependent hydrolysis of ATP to the release of the folded monomers of the target protein from chaperonin 60.
authors.affiliation: Central Research and Development Department, E. I. du Pont de Nemours and Company, Wilmington, Delaware 19880-0402.
authors.forename: P V
authors.initials: PV
authors.lastname: Viitanen
authors.forename: T H
authors.initials: TH
authors.lastname: Lubben
authors.forename: J
authors.initials: J
authors.lastname: Reed
authors.forename: P
authors.initials: P
authors.lastname: Goloubinoff
authors.forename: D P
authors.initials: DP
authors.lastname: O'Keefe
authors.forename: G H
authors.initials: GH
authors.lastname: Lorimer
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000378:metabolism*; D018833:Chaperonins; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism*; D006868:Hydrolysis; D011188:Potassium / Q000494:pharmacology*; D011487:Protein Conformation; D011506:Proteins / Q000378:metabolism*; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism*; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D011506:Proteins; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D018833:Chaperonins; D012273:Ribulose-Bisphosphate Carboxylase; D011188:Potassium