PP7 virus-like particles in E. coli imaged with the crossed laser phase plate (xLPP) at 0.5-1.5 µm underfocus

Escherichia coli cells overexpressing PP7 virus-like particles imaged on a Titan Krios G4 with the crossed laser phase plate (xLPP) switched on, close to focus at 0.5-1.5 µm target underfocus, as part of a matched-grid comparison with conventional underfocus phase contrast. Dose-symmetric tilt series (nominally ±45°, 3° steps, ~126 e/Ų total; one series stopped early) were collected using PACEtomo-based SerialEM scripts with electron-to-laser alignments for each tilt on a Gatan Celtic detector and processed with AreTomo3 (motion correction, CTF estimation with additional phase shift, patch-based alignment, SART and WBP reconstruction); PP7 VLP positions were picked with Octopi, curated by 2D classification or picked manually.