Chaperonin-facilitated refolding of ribulosebisphosphate carboxylase and ATP hydrolysis by chaperonin 60 (groEL) are K+ dependent.
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.
Viitanen
P V
PV
Central Research and Development Department, E. I. du Pont de Nemours and Company, Wilmington, Delaware 19880-0402.
Lubben
T H
TH
Reed
J
J
Goloubinoff
P
P
O'Keefe
D P
DP
Lorimer
G H
GH
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
D001426:Bacterial Proteins; D011506:Proteins; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D018833:Chaperonins; D012273:Ribulose-Bisphosphate Carboxylase; D011188:Potassium