title: Two-dimensional crystals of the molecular chaperone GroEL reveal structural plasticity.
abstract: For two-dimensional (2-D) crystallization we have purified the molecular chaperone GroEL from Escherichia coli to homogeneity. The final and important step for crystallization in the purification procedure was an ATP-agarose column, on which the spacer between ATP and agarose was attached to C8 of adenine. Using the mica spreading "negative staining-carbon film" procedure and polyethylene glycol as a precipitant, we obtained four different 2-D periodic arrays. Two of them turned out to be true crystals. One crystal has P2 symmetry and lattice constants of a = 24.3 nm and b = 16.9 nm, the other has essentially P4 symmetry and shows smoothly varying local changes in the lattice parameters (a = b = 23 (+/- 1.3) nm). Very striking in the P4 crystal is the departure within each individual GroEL particle from the GroEL-typical seven-fold symmetry, which seems to be required for GroEL to accommodate to a crystal symmetry.
authors.affiliation: Protein Engineering Group, Max-Planck-Institut für Biochemie Am Klopferspitz, Martinsried, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Zahn
authors.forename: J R
authors.initials: JR
authors.lastname: Harris
authors.forename: G
authors.initials: G
authors.lastname: Pfeifer
authors.forename: A
authors.initials: A
authors.lastname: Plückthun
authors.forename: W
authors.initials: W
authors.lastname: Baumeister
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D018834:Chaperonin 60; D003460:Crystallization; D006360:Heat-Shock Proteins / Q000737:chemistry*; D008854:Microscopy, Electron
chemical_list: D001426:Bacterial Proteins; D018834:Chaperonin 60; D006360:Heat-Shock Proteins