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2D and 3D crystallization of the wild-type IIC domain of the glucose PTS transporter from Escherichia coli

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Kalbermatter David, Jeckelmann Jean Marc, Chiu Po Lin, Ucurum Zöhre, Walz Thomas, Fotiadis Dimitrios,
Project Structure and supramolecular organization of membrane transport proteins
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Original article (peer-reviewed)

Journal Journal of Structural Biology
Volume (Issue) 191(3)
Page(s) 376 - 380
Title of proceedings Journal of Structural Biology
DOI 10.1016/j.jsb.2015.08.003


The bacterial phosphoenolpyruvate: sugar phosphotransferase system serves the combined uptake and phosphorylation of carbohydrates. This structurally and functionally complex system is composed of several conserved functional units that, through a cascade of phosphorylated intermediates, catalyze the transfer of the phosphate moiety from phosphoenolpyruvate to the substrate, which is bound to the integral membrane domain IIC. The wild-type glucose-specific IIC domain (wt-IIC(glc)) of Escherichia coli was cloned, overexpressed and purified for biochemical and functional characterization. Size-exclusion chromatography and scintillation-proximity binding assays showed that purified wt-IIC(glc) was homogenous and able to bind glucose. Crystallization was pursued following two different approaches: (i) reconstitution of wt-IIC(glc) into a lipid bilayer by detergent removal through dialysis, which yielded tubular 2D crystals, and (ii) vapor-diffusion crystallization of detergent-solubilized wt-IIC(glc), which yielded rhombohedral 3D crystals. Analysis of the 2D crystals by cryo-electron microscopy and the 3D crystals by X-ray diffraction indicated resolutions of better than 6Å and 4Å, respectively. Furthermore, a complete X-ray diffraction data set could be collected and processed to 3.93Å resolution. These 2D and 3D crystals of wt-IIC(glc) lay the foundation for the determination of the first structure of a bacterial glucose-specific IIC domain.