High salt-induced conversion of Escherichia coli GroEL into a fully functional thermophilic chaperonin.
The GroE chaperonin system can adapt to and function at various environmental folding conditions. To examine chaperonin-assisted protein folding at high salt concentrations, we characterized Escherichia coli GroE chaperonin activity in 1.2 m ammonium sulfate. Our data are consistent with GroEL undergoing a conformational change at this salt concentration, characterized by elevated ATPase activity and increased exposure of hydrophobic surface, as indicated by increased binding of the fluorophore bis-(5, 5')-8-anilino-1-naphthalene sulfonic acid to the chaperonin. The presence of the salt results in increased substrate stringency and dependence on the full GroE system for release and productive folding of substrate proteins. Surprisingly, GroEL is fully functional as a thermophilic chaperonin in high concentrations of ammonium sulfate and is stable at temperatures up to 75 degrees C. At these extreme conditions, GroEL can suppress aggregation and mediate refolding of non-native proteins.
Kusmierczyk
A R
AR
Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, Rhode Island 02912, USA.
Martin
J
J
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000817:Anilino Naphthalenesulfonates / Q000378:metabolism; D018835:Chaperonin 10 / Q000502:physiology; D018834:Chaperonin 60 / Q000502:physiology*; D049452:Green Fluorescent Proteins; D006358:Hot Temperature; D006868:Hydrolysis; D008164:Luminescent Proteins / Q000737:chemistry; D017510:Protein Folding; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology*
D000817:Anilino Naphthalenesulfonates; D018835:Chaperonin 10; D018834:Chaperonin 60; D008164:Luminescent Proteins; D000644:Quaternary Ammonium Compounds; D049452:Green Fluorescent Proteins; C035763:5,5'-bis(8-(phenylamino)-1-naphthalenesulfonate); D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases