Defining the TRiC/CCT interactome links chaperonin function to stabilization of newly made proteins with complex topologies.
Folding within the crowded cellular milieu often requires assistance from molecular chaperones that prevent inappropriate interactions leading to aggregation and toxicity. The contribution of individual chaperones to folding the proteome remains elusive. Here we demonstrate that the eukaryotic chaperonin TRiC/CCT (TCP1-ring complex or chaperonin containing TCP1) has broad binding specificity in vitro, similar to the prokaryotic chaperonin GroEL. However, in vivo, TRiC substrate selection is not based solely on intrinsic determinants; instead, specificity is dictated by factors present during protein biogenesis. The identification of cellular substrates revealed that TRiC interacts with folding intermediates of a subset of structurally and functionally diverse polypeptides. Bioinformatics analysis revealed an enrichment in multidomain proteins and regions of beta-strand propensity that are predicted to be slow folding and aggregation prone. Thus, TRiC may have evolved to protect complex protein topologies within its central cavity during biosynthesis and folding.
Yam
Alice Y
AY
Department of Biology and BioX Program, E200A James Clark Center, 318 Campus Drive, Stanford University, Stanford, California 94043, USA.
Xia
Yu
Y
Lin
Hen-Tzu Jill
HT
Burlingame
Alma
A
Gerstein
Mark
M
Frydman
Judith
J
D002478:Cells, Cultured; D056404:Chaperonin Containing TCP-1; D018833:Chaperonins / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008954:Models, Biological; D011485:Protein Binding; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry / Q000302:isolation & purification; D013379:Substrate Specificity
D011506:Proteins; C533304:TCP1 protein, human; D056404:Chaperonin Containing TCP-1; D018833:Chaperonins