Bacterial Proteins Associated With Cell Shape Homeostasis Localize to Specific 3D Geometries*

The bacterial kingdom exhibits a wide variety of cell shapes and sizes which are crucial for the lifestyle of each species. We have developed an image-processing framework that extracts precise 3D shapes from fluorescence microscopy data allowing us to calculate geometric parameters such as local curvature, surface area, and the relative enrichment of fluorescent signals. We use this to measure the geometric localization of proteins responsible for the characteristic shape of Gram-negative bacteria (straight rod Escherichia coli, curved rod Vibrio cholerae, and helical rod Helicobacter pylori). In E. coli, the bacterial actin MreB localizes away from positive Gaussian curvature and toward low curvature. Without the MreB modulator RodZ, MreB loses its curvature localization and cells lose their uniform rod-like shape. In cholera, CrvA localizes to areas of negative Gaussian curvature and slows the inner curve's growth, causing cells to curve. In the bacterial carcinogen H. pylori, we have begun to examine the localization of many cell shape determinants with various curvature preferences.