Open AccessA structural model for the GroEL chaperonin
Author(s) -
Marco Sergio,
Valpuesta JoséMaría,
Rivas Germán,
Andrés Germán,
San Martín Carmen,
Carrascosa JoséL.
Publication year - 1993
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1993.tb05980.x
Subject(s) - groel , chaperonin , homogeneous , groes , crystallography , population , particle (ecology) , chemistry , escherichia coli , biophysics , protein folding , biology , physics , biochemistry , thermodynamics , ecology , demography , sociology , gene
Individual particle analysis of end views from negatively stained specimensof 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.