title: TRiC/CCT cooperates with different upstream chaperones in the folding of distinct protein classes.
abstract: The role in protein folding of the eukaryotic chaperonin TRiC/CCT is only partially understood. Here, we show that a group of WD40 beta-propeller proteins in the yeast cytosol interact transiently with TRiC upon synthesis and require the chaperonin to reach their native state. TRiC cooperates in the folding of these proteins with the ribosome-associated heat shock protein (Hsp)70 chaperones Ssb1/2p. In contrast, newly synthesized actin and tubulins, the major known client proteins of TRiC, are independent of Ssb1/2p and instead use the co-chaperone GimC/prefoldin for efficient transfer to the chaperonin. GimC can replace Ssb1/2p in the folding of WD40 substrates such as Cdc55p, but combined deletion of SSB and GIM genes results in loss of viability. These findings expand the substrate range of the eukaryotic chaperonin by a structurally defined class of proteins and demonstrate an essential role for upstream chaperones in TRiC-assisted folding.
mesh_terms: D018797:Cell Cycle Proteins / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D018832:Molecular Chaperones / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D017510:Protein Folding; D054648:Protein Phosphatase 2; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases; D056427:t-Complex Genome Region
chemical_list: C071246:CDC55 protein, S cerevisiae; D018797:Cell Cycle Proteins; D018840:HSP70 Heat-Shock Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008869:Microtubule-Associated Proteins; D018832:Molecular Chaperones; D009687:Nuclear Proteins; C095192:SSB1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C112806:prefoldin; C116196:PPP1R11 protein, human; D044767:Ubiquitin-Protein Ligases; D054648:Protein Phosphatase 2