Skip to main content
[Preprint]. 2023 Mar 26:2023.03.25.534239. [Version 1] doi: 10.1101/2023.03.25.534239

Figure 1. CryoEM structure of the PhLP2A-open TRiC complex.

Figure 1.

(A) (Left) Schematic of the designed experiment. (Right) Front, slice, and top view of consensus ma p of PhLP2A encapsulated in the TRiC folding chamber. Each CCT subunit and PhLP2A are color c oded as defined in the top view. (B) Atomic model of the PhLP2A-TRiC complex from the front and top view. CCT subunits and PhLP2A are color coded as in (A). (C) Two binding modes of the PhLP 2A NTD are revealed by 3D-focused classification. (i) Densities of CCT3 or CCT4 bound to PhLP2A. (ii) Atomic models of the complexes of the PhLP2A NTD and CCT3 or CCT4 using Alphafold predi ction. Each domain of PhLP2A is color-coded: NTD: dodger blue, TXD: red, CTD: dark magenta. (D) (i) Schematic diagram of PhLP2A and the CCT3/4 complex. The colored box indicates the modeled residues of PhLP2A with each domain color-coded. (ii) Alphafold prediction of each complex with a per-residue confidence score (pLDDT) diagram. (iii) Sequence alignment of H9 and H10 of CCT3 an d CCT4 at the major interaction site of PhLP2A. Predicted interactions between CCTs and PhLP2A are labeled with black lines. (E) (i) 2D Topology diagram of PhLP2A. Each domain is color coded a s indicated in (C). (ii) Three representative structures of Alphafold-predicted full-length models of PhL P2A, color-coded in a domain-wise manner and (iii) superposition of the three models with the expe rimental model. (F) Intramolecular crosslinking of PhLP2A. (Left) Intramolecular crosslinks labeled on the PhLP2A model. (Top, right) 2D schematic diagram of intramolecular crosslinks on PhLP2A. N-ter minal helices which were unresolved in cryoEM structures crosslink to all the other domains. (Botto m right) Graph of Cα pair distance. (G) Intermolecular crosslinking between PhLP2A and CCT subun its. (i) Detailed representation of the crosslinks on the model. PhLP2A crosslinks to the residues on CCT subunits of the half hemisphere of CCT2/4/1/3/6. (ii) Schematic diagram showing intermolecular crosslinks between each domain of the PhLP2A and CCT subunit. (H) Schematic representation of PhLP2A topology in an open TRiC chamber. While CTD and TXD are anchored near the equatorial domain of CCT3/6, N-terminal helices can adopt various topologies and reside inside the folding cha mber.