title: Archaeal group II chaperonin mediates protein folding in the cis-cavity without a detachable GroES-like co-chaperonin.
abstract: Group II chaperonins of archaea and eukaryotes are distinct from group I chaperonins of bacteria. Whereas group I chaperonins require the co-chaperonin Cpn-10 or GroES for protein folding, no co-chaperonin has been known for group II. The protein folding mechanism of group II chaperonins is not yet clear. To understand this mechanism, we examined protein refolding by the recombinant alpha or beta-subunit chaperonin homo-oligomer (alpha16mer and beta16mer) from a hyperthermoplilic archaeum, Thermococcus strain KS-1, using a model substrate, green fluorescent protein (GFP). The alpha16mer and beta16mer captured the non-native GFP and promoted its refolding without any co-chaperonin in an ATP dependent manner. A non-hydrolyzable ATP analog, AMP-PNP, induced the GFP refolding mediated by beta16mer but not by the alpha16mer. A mutant alpha-subunit chaperonin homo-oligomer (trap-alpha) could capture the non-native protein but lacked the ability to refold it. Although trap-alpha suppressed ATP-dependent refolding of GFP mediated by alpha16mer or beta16mer, it did not affect the AMP-PNP-dependent refolding. This indicated that the GFP refolding mediated by beta16mer with AMP-PNP was not accessible to the trap-alpha. Gel filtration chromatography and a protease protection experiment revealed that this refolded GFP, in the presence of AMP-PNP, was associated with beta16mer. After the completion of GFP refolding mediated by beta16mer with AMP-PNP, addition of ATP induced an additional refolding of GFP. Furthermore, the beta16mer preincubated with AMP-PNP showed the ability to capture the non-native GFP. These suggest that AMP-PNP induced one of two chaperonin rings (cis-ring) to close and induced protein refolding in this ring, and that the other ring (trans-ring) could capture the unfolded GFP which was refolded by adding ATP. The present data indicate that, in the group II chaperonin of Thermococcus strain KS-1, the protein folding proceeds in its cis-ring in an ATP-dependent fashion without any co-chaperonin.
authors.affiliation: Kamaishi Laboratories, Marine Biotechnology Institute Co. Ltd., 3-75-1 Heita, Kamaishi, 026-0001, Iwate, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Yoshida
authors.forename: Rika
authors.initials: R
authors.lastname: Kawaguchi
authors.forename: Hideki
authors.initials: H
authors.lastname: Taguchi
authors.forename: Masasuke
authors.initials: M
authors.lastname: Yoshida
authors.forename: Takuo
authors.initials: T
authors.lastname: Yasunaga
authors.forename: Takeyuki
authors.initials: T
authors.lastname: Wakabayashi
authors.forename: Masafumi
authors.initials: M
authors.lastname: Yohda
authors.forename: Tadashi
authors.initials: T
authors.lastname: Maruyama
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D000266:Adenylyl Imidodiphosphate / Q000378:metabolism; D019843:Archaeal Proteins / Q000737:chemistry / Q000145:classification / Q000378:metabolism* / Q000648:ultrastructure; D002135:Calcium-Binding Proteins / Q000378:metabolism; D018835:Chaperonin 10 / Q000737:chemistry / Q000502:physiology; D018833:Chaperonins / Q000737:chemistry / Q000145:classification* / Q000378:metabolism* / Q000648:ultrastructure; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D002950:Citrate (si)-Synthase / Q000737:chemistry / Q000378:metabolism; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000737:chemistry / Q000378:metabolism; D008562:Membrane Glycoproteins; D008854:Microscopy, Electron; D008954:Models, Biological; D017510:Protein Folding; D020836:Protein Structure, Quaternary; D021122:Protein Subunits; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D018000:Receptors, Peptide / Q000378:metabolism; D012697:Serine Endopeptidases / Q000378:metabolism; D019712:Thermococcus / Q000737:chemistry* / Q000235:genetics; D013820:Thermolysin / Q000378:metabolism
chemical_list: D019843:Archaeal Proteins; D002135:Calcium-Binding Proteins; D018835:Chaperonin 10; D008164:Luminescent Proteins; D008562:Membrane Glycoproteins; D021122:Protein Subunits; D018160:Receptors, Cytoplasmic and Nuclear; D018000:Receptors, Peptide; C066973:signal sequence receptor; D049452:Green Fluorescent Proteins; D000266:Adenylyl Imidodiphosphate; D000255:Adenosine Triphosphate; D002950:Citrate (si)-Synthase; D012697:Serine Endopeptidases; C036813:lysyl endopeptidase; D013820:Thermolysin; D018833:Chaperonins