Cryo-electron tomography of the Rickettsia parkeri cell surface reveals OmpB is required for the S-layer

Deposition Overview

Cryo-electron tomography study of the obligate intracellular bacterium Rickettsia parkeri (strain Portsmouth) imaging its cell surface to investigate the paracrystalline surface (S-)layer. Wild-type (GFPAa) and ompB-null (ompBSTOP::tn transposon mutant) bacteria were imaged both within infected A549 human epithelial host cells and as purified bacteria, including cryo-FIB-milled lamellae, on a Titan Krios at 300 kV. Tomograms reveal a repetitive S-layer proximal to the outer membrane in wild-type cells that is absent in the ompB mutant, demonstrating that the outer-membrane protein OmpB is required for S-layer formation. The deposition comprises tilt series and tomograms across multiple magnifications and sample-preparation conditions.