A structural model for the GroEL chaperonin.
Individual particle analysis of end views from negatively stained specimens of purified GroEL from Escherichia coli showed the presence of two different particle populations, those with a six-fold symmetry and those with a seven-fold symmetry, when studied at pH 7.7 and 5.0. Image processing of particles from frozen-hydrated specimens revealed at both pH values a homogeneous population of particles with a strong seven-fold symmetry component and an average image with seven asymmetric units. Biochemical analysis of purified GroEL showed unequivocally the presence of a single polypeptide with the N-terminal sequence identical to that of GroEL. These results are compatible with a structural model of GroEL as an asymmetric aggregate built up by two rings of seven-fold and six-fold symmetries, respectively.
Marco
S
S
Centro de Biología Molecular, Universidad Autónoma de Madrid, Cantoblanco, Spain.
Valpuesta
J M
JM
Rivas
G
G
Andrés
G
G
San Martín
C
C
Carrascosa
J L
JL
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000648:ultrastructure*; D018834:Chaperonin 60; D004926:Escherichia coli / Q000737:chemistry / Q000235:genetics; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000648:ultrastructure*; D007091:Image Processing, Computer-Assisted; D008854:Microscopy, Electron; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation
D001426:Bacterial Proteins; D018834:Chaperonin 60; D006360:Heat-Shock Proteins