5FGD: Yeast 20s Proteasome Beta5-h(-2)l-t1a Double Mutant In Complex With Carfilzomib

Citation:
Abstract
Biogenesis of the 20S proteasome is tightly regulated. The N-terminal propeptides protecting the active-site threonines are autocatalytically released only on completion of assembly. However, the trigger for the self-activation and the reason for the strict conservation of threonine as the active site nucleophile remain enigmatic. Here we use mutagenesis, X-ray crystallography and biochemical assays to suggest that Lys33 initiates nucleophilic attack of the propeptide by deprotonating the Thr1 hydroxyl group and that both residues together with Asp17 are part of a catalytic triad. Substitution of Thr1 by Cys disrupts the interaction with Lys33 and inactivates the proteasome. Although a Thr1Ser mutant is active, it is less efficient compared with wild type because of the unfavourable orientation of Ser1 towards incoming substrates. This work provides insights into the basic mechanism of proteolysis and propeptide autolysis, as well as the evolutionary pressures that drove the proteasome to become a threonine protease.
PDB ID: 5FGDDownload
MMDB ID: 137726
PDB Deposition Date: 2015/12/20
Updated in MMDB: 2016/12
Experimental Method:
x-ray diffraction
Resolution: 2.8  Å
Source Organism:
Similar Structures:
Biological Unit for 5FGD: 28-meric; determined by author
Molecular Components in 5FGD
Label Count Molecule
Proteins (28 molecules)
2
Proteasome Subunit Alpha Type-2(Gene symbol: PRE8)
Molecule annotation
2
Proteasome Subunit Alpha Type-3(Gene symbol: PRE9)
Molecule annotation
2
Proteasome Subunit Alpha Type-4(Gene symbol: PRE6)
Molecule annotation
2
Proteasome Subunit Alpha Type-5(Gene symbol: PUP2)
Molecule annotation
2
Proteasome Subunit Alpha Type-6(Gene symbol: PRE5)
Molecule annotation
2
Probable Proteasome Subunit Alpha Type-7(Gene symbol: PRE10)
Molecule annotation
2
Proteasome Subunit Alpha Type-1(Gene symbol: SCL1)
Molecule annotation
2
Proteasome Subunit Beta Type-2(Gene symbol: PUP1)
Molecule annotation
2
Proteasome Subunit Beta Type-3(Gene symbol: PUP3)
Molecule annotation
2
Proteasome Subunit Beta Type-4(Gene symbol: PRE1)
Molecule annotation
2
Proteasome Subunit Beta Type-5(Gene symbol: PRE2)
Molecule annotation
2
Proteasome Subunit Beta Type-6(Gene symbol: PRE7)
Molecule annotation
2
Proteasome Subunit Beta Type-7(Gene symbol: PRE4)
Molecule annotation
2
Proteasome Subunit Beta Type-1(Gene symbol: PRE3)
Molecule annotation
Chemicals (18 molecules)
1
7
2
5
3
4
4
2
* Click molecule labels to explore molecular sequence information.

Citing MMDB
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