title: Folding intermediate binds to the bottom of bullet-shaped holo-chaperonin and is readily accessible to antibody.
abstract: Holo-chaperonin from Thermus thermophilus (Thermus holo-cpn) is a bullet-shaped particle where chaperonin-10 heptamer locates at one axial end of the cylindrical body of chaperonin-60 tetradecamer. Thermus holo-cpn promotes in-vitro folding of denatured 3-isopropylmalate dehydrogenase (IPMDH) from the same bacterium. We observed the complexes of Thermus holo-cpn and folding intermediates of IPMDH by immuno-electron microscopy after decoration by single layer labeling with anti-IPMDH IgG or by double layer labeling with anti-IPMDH IgG as first layer and antibodies against IgG as second layer. Images of the electron microscope showed that anti-IPMDH IgG was bound to the bottom end of the bullet-shaped Thermus holo-cpn. This result provides direct evidence that the folding intermediate binds to the axial end, which is opposite to the end where chaperonin-10 heptamer resides, of the cylindrical body of chaperonin-60 tetradecamer, and that bound folding intermediate in the complex is sufficiently exposed to the outside to be accessible by antibody.
authors.affiliation: Frontier Research Program, Institute of Physical and Chemical Research RIKEN, Saitama, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Ishii
authors.forename: H
authors.initials: H
authors.lastname: Taguchi
authors.forename: H
authors.initials: H
authors.lastname: Sasabe
authors.forename: M
authors.initials: M
authors.lastname: Yoshida
mesh_terms: D050539:3-Isopropylmalate Dehydrogenase; D000429:Alcohol Oxidoreductases / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D000906:Antibodies; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D001666:Binding Sites, Antibody; D018835:Chaperonin 10; D002850:Chromatography, Gel; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000378:metabolism; D007074:Immunoglobulin G; D016253:Microscopy, Immunoelectron; D017510:Protein Folding; D016963:Thermus thermophilus / Q000201:enzymology / Q000378:metabolism*
chemical_list: D000906:Antibodies; D001426:Bacterial Proteins; D018835:Chaperonin 10; D006360:Heat-Shock Proteins; D007074:Immunoglobulin G; D000429:Alcohol Oxidoreductases; D050539:3-Isopropylmalate Dehydrogenase