PDBsum entry 1f9j

Chaperone

PDB id: 1f9j

Contents

Protein chains

76 a.a. *

* Residue conservation analysis

PDB id:

1f9j

Name:

Chaperone

Title:

Structure of a new crystal form of tetraubiquitin

Structure:

Tetraubiquitin. Chain: a, b. Synonym: ubiquitin. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

2.70Å R-factor: 0.225 R-free: 0.292

Authors:

C.L.Phillips,J.Thrower,C.M.Pickart,C.P.Hill

Key ref:

C.L.Phillips et al. (2001). Structure of a new crystal form of tetraubiquitin. Acta Crystallogr D Biol Crystallogr, 57, 341-344. PubMed id: 11173499 DOI: 10.1107/S090744490001800X

Date:

10-Jul-00 Release date: 07-Feb-01

Protein chains

P0CG48  (UBC_HUMAN) -  Polyubiquitin-C from Homo sapiens

Seq: 685 a.a.

Struc: 76 a.a.

DOI no: 10.1107/S090744490001800X

Acta Crystallogr D Biol Crystallogr 57:341-344 (2001)

PubMed id: 11173499

Structure of a new crystal form of tetraubiquitin.

C.L.Phillips, J.Thrower, C.M.Pickart, C.P.Hill.

ABSTRACT

Polyubiquitin chains, in which the C-terminus and a lysine side chain of successive ubiquitin molecules are linked by an isopeptide bond, function to target substrate proteins for degradation by the 26S proteasome. Chains of at least four ubiquitin moieties appear to be required for efficient recognition by the 26S proteasome, although the conformations of the polyubiquitin chains recognized by the proteasome or by other enzymes involved in ubiquitin metabolism are currently unknown. A new crystal form of tetraubiquitin, which has two possible chain connectivities that are indistinguishable in the crystal, is reported. In one possible connectivity, the tetraubiquitin chain is extended and packs closely against the antiparallel neighbor chain in the crystal to conceal a hydrophobic surface implicated in 26S proteasome recognition. In the second possibility, the tetraubiqutitin forms a closed compact structure, in which that same hydrophobic surface is buried. Both of these conformations are quite unlike the structure of tetraubiquitin that was previously determined in a different crystal form [Cook et al. (1994), J. Mol. Biol. 236, 601--609]. The new structure suggests that polyubiquitin chains may possess a substantially greater degree of conformational flexibility than has previously been appreciated.

Selected figure(s)

Figure 1.
Figure 1 The flexible linkages between ubiquitin moieties. Superposition of the first ubiquitin moiety of each of the three polyubiquitin crystal structures reveals each of the second ubiquitin moieties to be in a different position. The Ub[4]-2 dimer is shown in red, the Ub[4]-1 dimer in green and the Ub[2] dimer in blue. In each case, the Gly76-Lys148 linkage is shown in CPK representation. The N- and C-termini of the second ubiquitin moiety in each structure are labeled. Figures were created using MOLSCRIPT (Kraulis, 1991[Kraulis, P. J. (1991). J. Appl. Cryst. 24, 946-950.]).

The above figure is reprinted by permission from the IUCr: Acta Crystallogr D Biol Crystallogr (2001, 57, 341-344) copyright 2001.

Figure was selected by an automated process.