title: The Cpn10(1) co-chaperonin of A. thaliana functions only as a hetero-oligomer with Cpn20.
abstract: The A. thaliana genome encodes five co-chaperonin homologs, three of which are destined to the chloroplast. Two of the proteins, Cpn10(2) and Cpn20, form functional homo-oligomers in vitro. In the current work, we present data on the structure and function of the third A. thaliana co-chaperonin, which exhibits unique properties. We found that purified recombinant Cpn10(1) forms inactive dimers in solution, in contrast to the active heptamers that are formed by canonical Cpn10s. Additionally, our data demonstrate that Cpn10(1) is capable of assembling into active hetero-oligomers together with Cpn20. This finding was reinforced by the formation of active co-chaperonin species upon mixing an inactive Cpn20 mutant with the inactive Cpn10(1). The present study constitutes the first report of a higher plant Cpn10 subunit that is able to function only upon formation of hetero-oligomers with other co-chaperonins.
authors.affiliation: Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Anna
authors.initials: A
authors.lastname: Vitlin Gruber
authors.affiliation: Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Gal
authors.initials: G
authors.lastname: Zizelski
authors.affiliation: Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Abdussalam
authors.initials: A
authors.lastname: Azem
authors.affiliation: Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Celeste
authors.initials: C
authors.lastname: Weiss
mesh_terms: D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018833:Chaperonins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D056384:Group I Chaperonins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D009154:Mutation; D055503:Protein Multimerization; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C000604276:Cpn10(1) protein, Arabidopsis; C478767:Cpn20 protein, Arabidopsis; D021122:Protein Subunits; D018833:Chaperonins; D056384:Group I Chaperonins