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Figure 4
Serial synchrotron crystallography structure of serine β-lactamase CTX-M-15, originally found in Klebsiella pneumoniae IS53, determined using our tape drive system on VMXi. (a) Diffraction pattern measured from ∼8 µm microcrystals within ∼500 pl droplets on a tape moving at 0.25 m s−1 with 2 ms total exposure time, during which crystals were in the 16 keV X-ray beam (10 × 10 µm, pink beam) for a maximum of ∼720 µs. (Top inset) Expanded regions of the detector image with an example spot profile for a ∼2.1 Å reflection and (bottom inset) an indication of the background levels, showing the pixel intensity across the region where the tape scattering may be observed. (b) The 2Fo − Fc electron-density map at 1.83 Å resolution shown as a blue mesh contoured at 1.2σ. The carbon reading atoms of key active site residues are coloured green and labelled. Sulfate (labelled) from the crystallization condition is bound at the active site; the catalytic deacyl­ating water is labelled DW and hydrogen-bonded to Ser70, Glu166 and Asn170. The figure was created in PyMol (https://www.pymol.org/). (c) 2mFo − DFc composite omit map with 5000 K Cartesian simulated annealing (created in Phenix with 5% of atoms omitted at each step) of the 1.83 Å resolution CTX-M-15 data, shown as a grey mesh contoured at 1.2σ.

IUCrJ
Volume 13| Part 5| September 2026|
ISSN: 2052-2525
https://doi.org/10.1107/S2052252526005658