8XIL image
Deposition Date 2023-12-19
Release Date 2024-12-25
Last Version Date 2025-07-09
Entry Detail
PDB ID:
8XIL
Keywords:
Title:
Cellodextrin phosphorylase from Clostridium thermocellum mutant - all cysteine residues were substituted with serines
Biological Source:
Source Organism:
Method Details:
Experimental Method:
Resolution:
1.21 Å
R-Value Free:
0.16
R-Value Work:
0.14
R-Value Observed:
0.14
Space Group:
P 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Molecule:Cellodextrin phosphorylase
Gene (Uniprot):cdp-ym4
Chain IDs:A, B
Chain Length:992
Number of Molecules:2
Biological Source:Acetivibrio thermocellus
Peptide-like Molecules
PRD_900021
Primary Citation
Effect of Free Cysteine Residues to Serine Mutation on Cellodextrin Phosphorylase.
J Appl Glycosci (1999) 71 37 46 (2024)
PMID: 38863949 DOI: 10.5458/jag.jag.JAG-2023_0011

Abstact

Cellodextrin phosphorylase (CDP) plays a key role in energy-efficient cellulose metabolism of anaerobic bacteria by catalyzing phosphorolysis of cellodextrin to produce cellobiose and glucose 1-phosphate, which can be utilized for glycolysis without consumption of additional ATP. As the enzymatic phosphorolysis reaction is reversible, CDP is also employed to produce cellulosic materials in vitro. However, the enzyme is rapidly inactivated by oxidation, which hinders in vitro utilization in aerobic environments. It has been suggested that the cysteine residues of CDP, which do not form disulfide bonds, are responsible for the loss of activity, and the aim of the present work was to test this idea. For this purpose, we replaced all 11 free cysteine residues of CDP from Acetivibrio thermocellus (formerly known as Clostridium thermocellum) with serine, which structurally resembles cysteine in our previous work. Herein, we show that the resulting CDP variant, named CDP-CS, has comparable activity to the wild-type enzyme, but shows increased stability to oxidation during long-term storage. X-Ray crystallography indicated that the mutations did not markedly alter the overall structure of the enzyme. Ensemble refinement of the crystal structures of CDP and CDP-CS indicated that the C372S and C625S mutations reduce structural fluctuations in the protein main chain, which may contribute to the increased stability of CDP-CS to oxidation.

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Primary Citation of related structures