Role of the GroEL chaperonin intermediate domain in coupling ATP hydrolysis to polypeptide release.
Modification of the Escherichia coli chaperonin GroEL with N-ethylmaleimide at residue Cys138 affects the structural and functional integrity of the complex. Nucleotide affinity and ATPase activity of the modified chaperonin are increased, whereas cooperativity of ATP hydrolysis and affinity for GroES are reduced. As a consequence, release and folding of substrate proteins are strongly impaired and uncoupled from ATP hydrolysis in a temperature-dependent manner. Folding of dihydrofolate reductase at 25 degrees C becomes dependent on GroES, whereas folding of typically GroES-dependent proteins is blocked completely. At 37 degrees C, GroES binding is restored to normal levels, and the modified GroEL regains its chaperone activity to some extent. These results assign a central role to the intermediate GroEL domain for transmitting conformational changes between apical and central domains, and for coupling ATP hydrolysis to productive protein release.
Martin
J
J
Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Box G-J2, Providence, Rhode Island 02912, USA. Jorg_Martin@Brown.edu
D000255:Adenosine Triphosphate / Q000378:metabolism*; D018835:Chaperonin 10 / Q000378:metabolism; D018834:Chaperonin 60 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000378:metabolism; D004926:Escherichia coli; D005033:Ethylmaleimide / Q000494:pharmacology; D006868:Hydrolysis; D016254:Mutagenesis, Insertional; D016133:Polymerase Chain Reaction; D011487:Protein Conformation; D017510:Protein Folding; D013329:Structure-Activity Relationship; D013439:Sulfhydryl Reagents / Q000494:pharmacology
D018835:Chaperonin 10; D018834:Chaperonin 60; D013439:Sulfhydryl Reagents; D000255:Adenosine Triphosphate; D003545:Cysteine; D005033:Ethylmaleimide