Hydrophilic residues at the apical domain of GroEL contribute to GroES binding but attenuate polypeptide binding.
The GroES binding site at the apical domain of GroEL, mostly consisting of hydrophobic residues, overlaps largely with the substrate polypeptide binding site. Essential contribution of hydrophobic interaction to the binding of both GroES and polypeptide was exemplified by the mutant GroEL(L237Q) which lost the ability to bind either of them. The binding site, however, contains three hydrophilic residues, E238, T261, and N265. For GroES binding, N265 is essential since GroEL(N265A) is unable to bind GroES. E238 contributes to rapid GroES binding to GroEL because GroEL(E238A) is extremely sluggish in GroES binding. Polypeptide binding was not impaired by any mutations of E238A, T261A, and N265A. Rather, these mutants, especially GroEL(N265A), showed stronger polypeptide binding affinity than wild-type GroEL. Thus, these hydrophilic residues have a dual role; they help GroES binding on one hand but attenuate polypeptide binding on the other hand.
Motojima
F
F
Research Laboratory of Resources Utilization, Tokyo Institute of Technology, Nagatsuta 4259, Midori-ku, Yokohama, 226-8503, Japan.
Makio
T
T
Aoki
K
K
Makino
Y
Y
Kuwajima
K
K
Yoshida
M
M
D000251:Adenosine Triphosphatases / Q000378:metabolism; D019943:Amino Acid Substitution; D001665:Binding Sites; D018835:Chaperonin 10 / Q000378:metabolism*; D018834:Chaperonin 60 / Q000737:chemistry* / Q000378:metabolism*; D005456:Fluorescent Dyes; D049452:Green Fluorescent Proteins; D007700:Kinetics; D008164:Luminescent Proteins / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D010455:Peptides / Q000378:metabolism*; D011487:Protein Conformation; D017510:Protein Folding; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013762:Tetrahydrofolate Dehydrogenase / Q000737:chemistry / Q000378:metabolism; D013884:Thiosulfate Sulfurtransferase / Q000378:metabolism
D018835:Chaperonin 10; D018834:Chaperonin 60; D005456:Fluorescent Dyes; D008164:Luminescent Proteins; D010455:Peptides; D011994:Recombinant Proteins; D049452:Green Fluorescent Proteins; D013762:Tetrahydrofolate Dehydrogenase; D013884:Thiosulfate Sulfurtransferase; D000251:Adenosine Triphosphatases