Superresolution Investigation of the Dynamics of FtsZ Structures during E. Coli Cell Division

Abstract

FtsZ is an E. coli tubulin homolog that forms single-stranded protofilaments that can interact laterally to form superstructures. In vivo, FtsZ localizes to the midcell plane and assembles into a ring-like structure known as the Z-ring, which is necessary for cell division. The Z-ring serves as an scaffold to recruit all other division proteins and may also generate contractile force for cytokinesis. However, details about the arrangement of protofilaments within the Z-ring, which would suggest possible contraction mechanisms, remains unclear. We have used photoactivated localization microscopy (PALM) to characterize the in vivo structural dynamics of the Z-ring in E. coli at a spatial resolution of ∼35 nm. Using Photoactivated Localization Microscopy (PALM), we have previously shown that the Z-ring is a loose bundle of overlapping protofilaments that form either a single-ring conformation at midcell or a multiple-ring conformation reminiscent of a tight helix. We are currently investigating the structural changes that the Z-ring undergoes during the cell cycle and the role of GTPase activity in the structural rearrangements using the variant FtsZ84, which has diminished GTPase activity in vitro.