In vivo Architecture of the Polar Organizing Protein Z (PopZ) Meshwork in the Alphaproteobacteria Magnetospirillum gryphiswaldense and Caulobacter crescentus

The polar organizing protein Z (PopZ) forms a polar microdomain that is inaccessible to larger macromolecules such as ribosomes, and selectively sequesters proteins crucial for cell cycle control and polar morphogenesis in various Alphaproteobacteria. However, the in vivo architecture of this microdomain has remained elusive. Here, we analyzed the three-dimensional ultrastructural organization of the PopZ network in Magnetospirillum gryphiswaldense and Caulobacter crescentus by Volta phase plate cryoelectron tomography, which provides high spatial resolution and improved image contrast. Our results suggest that PopZ forms a porous network of disordered short, flexible, and branching filaments.(c) 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).