8XI1

Cellodextrin phosphorylase from Clostridium thermocellum mutant - all cysteine residues were substituted with serines

Replaces:  8H2K

Summary for 8XI1

• Entry DOI: 10.2210/pdb8xi1/pdb
• Descriptor: cellodextrin phosphorylase variant, GLYCEROL, DI(HYDROXYETHYL)ETHER, ... (6 entities in total)
• Functional Keywords: cellulose, cellodextrin, synthesis, phosphorolysis, carbohydrate
• Biological source: Acetivibrio thermocellus
• Total number of polymer chains: 2
• Total formula weight: 226151.69

Authors

Kuga, T.,Sunagawa, N.,Igarashi, K. (deposition date: 2023-12-19, release date: 2024-12-25, Last modification date: 2025-07-09)

Primary citation

Kuga, T.,Sunagawa, N.,Igarashi, K.
Effect of Free Cysteine Residues to Serine Mutation on Cellodextrin Phosphorylase.
J Appl Glycosci (1999), 71:37-46, 2024

PubMed Abstract: 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 However, the enzyme is rapidly inactivated by oxidation, which hinders 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 (formerly known as ) 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.

PubMed: 38863949
DOI: 10.5458/jag.jag.JAG-2023_0011

Experimental method

X-RAY DIFFRACTION (1.37 Å)