May 19th, Professor Jie Xiao of Johns Hopkins Talk Annoucement

Title: Bacterial cell division in superresolution

Speaker: Dr. Jie Xiao

               Associate Professor, School of Medicine, University of Johns Hopkins

Time: 10:00 ~11:00 AM, June 19th, 2014

Venue: Rm. 302, Integrated Science Research Center

Contact: Dr. Lei Huang,62751884,

Email: leihuangmed@gmail.com



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.

Professor Xiao is an Associate Professor of Biophysics and Biophysical Chemistry in the School of Medicine at Johns Hopkins. Her research is focusing on single-molecule studies in bacterial cells, dynamics and structure of the division complex, spacial organization and dynamics of transcription and noise control mechanisms in gene regulatory networks. She is a former postdoctoral fellow in Sunney’s group.


Below is her selected publication for your reference.

1. Buss J., Coltharp C., Huang T., Pohlmeyer C., Hatem C., Xiao J., In vivo organization of the FtsZ-ring by ZapA and ZapB revealed by quantitative super-resolution microscopy, 2013, Mol. Microbio. Jul 17. 89(6), 1099-1120 (pdf)

2. Hensel Z.,Weng X., Lagda A., Xiao J., Transcription factor mediated DNA looping probed by high-resolution, single-molecule imaging in live E. coli cells, 2013, PLoS Biology, 11(6):e1001591 (pdf) ? Editors Synopsis*

3. Hensel Z., Xiao J., Single molecule methods for studying gene regulation in vivo, Pflügers Arch-European Journal of Physiology, 2013, Mar;465(3):383-95 (pdf)

4. Buss J., Coltharp C., Xiao J., Super-Resolution Imaging of the Bacterial Division Machinery. J. Vis. Exp. 2013, (71), e50048, doi:10.3791/50048 (pdf)

5. Hensel Z., Fang X., Xiao J., Single-molecule imaging of gene regulation in vivo using Co-Translational Activation by Cleavage (CoTrAC), J. Vis. Exp. 2013, Mar 15;(73):e50042. doi: 10.3791/50042 (pdf)

6. Coltharp C. Kessler R., Xiao J., Accurate construction of photoactivated localization microscopy (PALM) images for quantitative measurements, PLoS One, 2012;7(12):e51725. doi: 10.1371 (pdf)

7. Coltharp C, Xiao J., Superresolution microscopy for microbiology, Cell Microbiol, 2012, 14(12):1808-18 (pdf)

8. Hensel Z., Feng H., Han B., Hatem C., Wang J*., Xiao J.*, Stochastic expression dynamics of transcription factor revealed by single-molecule noise analysis, 2012, Nat. Struct. Mol. Biol. 19(8):797-802, *cocorresponding authors. (pdf) ? International Innovation Interview with Jie Xiao*

9. Feng H., Hensel Z., Xiao J.*, Wang J.*, Analytical calculation of protein production distributions in models of clustered protein expression, Phys Rev Lett E, 2012, 85(3), 031904 *cocorresponding authors (pdf)

10. Guo F., Huang T., Buss J., Coltharp C., Hensel Z., Xiao J., In vivo structure of the E. coli FtsZ-ring revealed by photoactivated Localization Microscopy (PALM), 2010, PLoS One, 5, e12680 (pdf)

11. Xiao J., Single molecule imaging in live cells. Handbook of Single-molecule Biophysics, edited by van Oijen A., and Hinterdorfer P, 2009, Springer, NY