Identification of the TRiC/CCT substrate binding sites uncovers the function of subunit diversity in eukaryotic chaperonins.
The ring-shaped hetero-oligomeric chaperonin TRiC/CCT uses ATP to fold a diverse subset of eukaryotic proteins. To define the basis of TRiC/CCT substrate recognition, we mapped the chaperonin interactions with the VHL tumor suppressor. VHL has two well-defined TRiC binding determinants. Each determinant contacts a specific subset of chaperonin subunits, indicating that TRiC paralogs exhibit distinct but overlapping specificities. The substrate binding site in these subunits localizes to a helical region in the apical domains that is structurally equivalent to that of bacterial chaperonins. Transferring the distal portion of helix 11 between TRiC subunits suffices to transfer specificity for a given substrate motif. We conclude that the architecture of the substrate binding domain is evolutionarily conserved among eukaryotic and bacterial chaperonins. The unique combination of specificity and plasticity in TRiC substrate binding may diversify the range of motifs recognized by this chaperonin and contribute to its unique ability to fold eukaryotic proteins.
Spiess
Christoph
C
Department of Biological Sciences and BioX Program, Stanford University, Stanford, CA 94305, USA.
Miller
Erik J
EJ
McClellan
Amie J
AJ
Frydman
Judith
J
D020816:Amino Acid Motifs; D001665:Binding Sites; D018833:Chaperonins / Q000737:chemistry / Q000502:physiology*; D005057:Eukaryotic Cells / Q000378:metabolism*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D017510:Protein Folding; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000145:classification / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D013379:Substrate Specificity; D051794:Von Hippel-Lindau Tumor Suppressor Protein / Q000378:metabolism
D021122:Protein Subunits; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D018833:Chaperonins