Chaperone activity and structure of monomeric polypeptide binding domains of GroEL.
The chaperonin GroEL is a large complex composed of 14 identical 57-kDa subunits that requires ATP and GroES for some of its activities. We find that a monomeric polypeptide corresponding to residues 191 to 345 has the activity of the tetradecamer both in facilitating the refolding of rhodanese and cyclophilin A in the absence of ATP and in catalyzing the unfolding of native barnase. Its crystal structure, solved at 2.5 A resolution, shows a well-ordered domain with the same fold as in intact GroEL. We have thus isolated the active site of the complex allosteric molecular chaperone, which functions as a "minichaperone." This has mechanistic implications: the presence of a central cavity in the GroEL complex is not essential for those representative activities in vitro, and neither are the allosteric properties. The function of the allosteric behavior on the binding of GroES and ATP must be to regulate the affinity of the protein for its various substrates in vivo, where the cavity may also be required for special functions.
Zahn
R
R
Cambridge Centre for Protein Engineering, Department of Chemistry, University of Cambridge, United Kingdom.
Buckle
A M
AM
Perrett
S
S
Johnson
C M
CM
Corrales
F J
FJ
Golbik
R
R
Fersht
A R
AR
D000494:Allosteric Regulation; D000591:Amino Acid Isomerases / Q000737:chemistry* / Q000378:metabolism; D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D018834:Chaperonin 60 / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D017931:DNA Primers; D004926:Escherichia coli / Q000378:metabolism; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D019696:Peptidylprolyl Isomerase; D016133:Polymerase Chain Reaction; D011489:Protein Denaturation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D013884:Thiosulfate Sulfurtransferase / Q000737:chemistry / Q000378:metabolism
D002352:Carrier Proteins; D018834:Chaperonin 60; D017931:DNA Primers; D010446:Peptide Fragments; D011994:Recombinant Proteins; D013884:Thiosulfate Sulfurtransferase; D000591:Amino Acid Isomerases; D019696:Peptidylprolyl Isomerase