SciLifeLab The Svedberg seminar series 2014-06-02


Jie Xiao

Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, School of Medicine, Baltimore, MD, US

Home page: http://biophysics.med.jhmi.edu/xiao/index.html

Bacterial cell division in superresolution

Cell division is essential for the survival and development of all organisms. In prokaryotes, the FtsZ protein, a tubulin-like GTPase, plays a central role. FtsZ is highly conserved across bacterial species and has been identified as a novel drug target for antimicrobial therapy. In vivo FtsZ assembles into a supramolecular ring-like structure (hence named the Z-ring) at the leading edge of the invaginating membrane. The Z-ring serves as an essential scaffold to recruit all other division proteins and generates contractile force for cytokinesis. Despite the essential role of the Z-ring in bacterial cell division, it is not known what the structure of the Z-ring is or how the contractile force is generated.

We employ the newly developed single-molecule-based superresolution imaging technique to characterize the three-dimensional structure of the Z-ring in E. coli. We found that the Z-ring is likely composed of a loose bundle of FtsZ protofilaments that randomly overlap with each other in three dimensions. During constriction, the Z-ring condenses and finally collapses toward the end of septum closure . Furthermore, we found that the Z-ring is secured in a multi-layered protein network extending from membrane to chromosome. This extended protein network may play important roles in placing the Z-ring at the midcell, maintaining its structural integrity, and coordinate cell wall constriction with chromosome segregation.

Host: Johan Elf