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Updated: May 9, 2026
Production, Crystallization and Structure Determination of C. difficile PPEP-1 via Microseeding and Zinc-SAD
Published on: December 30, 2016
Protein expression, crystallization and preliminary X-ray crystallographic analysis of the isolated Shigella flexneri
Kehan Xu1, Emil Dedic, Patricia Cob-Cantal
1Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10c, DK-8000 Aarhus C, Denmark.
Abstract:
Upon release from the stable complex formed with its antitoxin VapB, the toxin VapC (MvpT) of the Gram-negative pathogen Shigella flexneri is capable of globally down-regulating translation by specifically cleaving initiator tRNA(fMet) in the anticodon region. Recombinant Shigella flexneri VapC(D7A) harbouring an active-site mutation was overexpressed in Escherichia coli, purified to homogeneity and crystallized by the vapour-diffusion technique. A preliminary X-ray crystallographic analysis shows that the crystals diffracted to at least 1.9 Å resolution at a synchrotron X-ray source and belonged to the trigonal space group in the hexagonal setting, H3, with unit-cell parameters a = b = 120.1, c = 52.5 Å, α = β = 90, γ = 120°. The Matthews coefficient is 2.46 Å(3) Da(-1), suggesting two molecules per asymmetric unit and corresponding to a solvent content of 50.0%.
Insights
Shigella flexneri toxin VapC cleaves initiator tRNA to stop translation. Researchers crystallized a VapC mutant to study its structure and function in bacterial pathogenesis.
Area of Science:
- Microbiology
- Structural Biology
- Biochemistry
Background:
- Shigella flexneri is a Gram-negative pathogen causing bacillary dysentery.
- The toxin VapC (MvpT) inhibits bacterial translation by cleaving initiator tRNA (tRNA(fMet)).
- VapC forms a complex with its antitoxin VapB, regulating its activity.
Purpose of the Study:
- To obtain structural insights into the VapC toxin.
- To investigate the mechanism of VapC-mediated translation inhibition.
- To characterize a catalytically inactive VapC mutant.
Main Methods:
- Overexpression and purification of recombinant Shigella flexneri VapC(D7A) in Escherichia coli.
- Crystallization of VapC(D7A) using the vapour-diffusion technique.
- Preliminary X-ray crystallographic analysis of VapC(D7A) crystals.
Main Results:
- Crystals of VapC(D7A) diffracted X-rays to at least 1.9 Å resolution.
- The crystals belonged to the trigonal space group H3.
- Unit-cell parameters and solvent content were determined, indicating two molecules per asymmetric unit.
Conclusions:
- The study provides a foundation for determining the high-resolution structure of VapC.
- Structural information will aid in understanding VapC's mechanism of tRNA cleavage.
- This research contributes to the study of bacterial toxins and potential therapeutic targets.
