PDBsum entry 3c91

Hydrolase

PDB id: 3c91

Contents

Protein chains

(+ 8 more) 227 a.a. *

(+ 8 more) 203 a.a. *

* Residue conservation analysis

PDB id:

3c91

Name:

Hydrolase

Title:

Thermoplasma acidophilum 20s proteasome with an open gate

Structure:

Proteasome subunit alpha. Chain: a, b, c, d, e, f, g, o, p, q, r, s, t, u. Synonym: multicatalytic endopeptidase complex subunit alpha. Engineered: yes. Proteasome subunit beta. Chain: h, i, j, k, l, m, n, v, w, x, y, z, 1, 2. Synonym: multicatalytic endopeptidase complex subunit beta. Engineered: yes

Source:

Thermoplasma acidophilum. Organism_taxid: 2303. Expressed in: escherichia coli. Expression_system_taxid: 562. Expression_system_taxid: 562

Authors:

J.Rabl,D.M.Smith,Y.Yu,S.C.Chang,A.L.Goldberg,Y.Cheng

Key ref:

J.Rabl et al. (2008). Mechanism of gate opening in the 20S proteasome by the proteasomal ATPases. Mol Cell, 30, 360-368. PubMed id: 18471981 DOI: 10.1016/j.molcel.2008.03.004

Date:

14-Feb-08 Release date: 05-Aug-08

Protein chains

P25156  (PSA_THEAC) -  Proteasome subunit alpha from Thermoplasma acidophilum (strain ATCC 25905 / DSM 1728 / JCM 9062 / NBRC 15155 / AMRC-C165)

Seq: 233 a.a.

Struc: 227 a.a.

Protein chains

P28061  (PSB_THEAC) -  Proteasome subunit beta from Thermoplasma acidophilum (strain ATCC 25905 / DSM 1728 / JCM 9062 / NBRC 15155 / AMRC-C165)

Seq: 211 a.a.

Struc: 203 a.a.

Enzyme reactions

• Enzyme class: Chains A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, 1, 2: E.C.3.4.25.1 - proteasome endopeptidase complex.
• Reaction: Cleavage at peptide bonds with very broad specificity.

DOI no: 10.1016/j.molcel.2008.03.004

Mol Cell 30:360-368 (2008)

PubMed id: 18471981

Mechanism of gate opening in the 20S proteasome by the proteasomal ATPases.

J.Rabl, D.M.Smith, Y.Yu, S.C.Chang, A.L.Goldberg, Y.Cheng.

ABSTRACT

Substrates enter the cylindrical 20S proteasome through a gated channel that is regulated by the ATPases in the 19S regulatory particle in eukaryotes or the homologous PAN ATPase complex in archaea. These ATPases contain a conserved C-terminal hydrophobic-tyrosine-X (HbYX) motif that triggers gate opening upon ATP binding. Using cryo-electron microscopy, we identified the sites in the archaeal 20S where PAN's C-terminal residues bind and determined the structures of the gate in its closed and open forms. Peptides containing the HbYX motif bind to 20S in the pockets between neighboring alpha subunits where they interact with conserved residues required for gate opening. This interaction induces a rotation in the alpha subunits and displacement of a reverse-turn loop that stabilizes the open-gate conformation. This mechanism differs from that of PA26/28, which lacks the HbYX motif and does not cause alpha subunit rotation. These findings demonstrated how the ATPases' C termini function to facilitate substrate entry.

Selected figure(s)

Figure 3.
Figure 3. Conformational Change of 20S α Ring Induced by the Gate-Opening Peptides
(A) Top view of superimposed density maps of 20S (gold mesh) and 20S-AHLDVLYA complex (blue transparent surface).
(B) Top view of the 20S-AHLDVLYA density map (blue) with the structure of the open-gate 20S docked.
(C) Top view of the 20S density map (gold) with the structure of the closed-gate 20S docked.
(D) Superimposed structures of 20S with the open and the closed gate.

Figure 6.
Figure 6. Mechanism of Gate Opening in the 20S Induced by PAN and PA26 Complexes
(A) (Left) Overlay of the α ring structures, before and after the binding of the gate-opening peptides. (Right) Enlarged view of the dashed area from the left. Pro17 is shifted because of the rotation in α subunit.
(B) (Left) Overlay of the structure of the α ring, before and after PA26 binding. (Right) Enlarged view of the dashed area. Pro17 is shifted by the activation loop of PA26 (data not shown). Notice that Pro17 in red and magenta structures is in a similar position.

The above figures are reprinted by permission from Cell Press: Mol Cell (2008, 30, 360-368) copyright 2008.

Figures were selected by the author.