The long-term goal of this application is to unravel mechanisms underlying the precise molecular controls of bacterial cell division. The project described here, centered on the FtsZ protein, is the first step toward this goal. 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 to drive cell division. The objective of this project is to determine the structure of the Z-ring, in particular the arrangement of protofilaments inside the Z-ring (Aim 1), and to identify the contraction mechanism of the Z-ring (Aim 2).
In Aim 1, using a single-molecule based superresolution imaging technique the Z-ring was imaged with a 30-nm spatial resolution. A 3D bundle arrangement of FtsZ protofilaments instead of a 2D flat ribbon was proposed. Such an arrangement model will be further verified by examining three predictions stemmed from the model. The final product of this aim is a high resolution Z-ring structural model that will be instrumental in understanding the contraction mechanism of the Z-ring.
In Aim 2, two competing Z-ring contraction mechanisms-disassembly vs. condensation-will be examined. The contraction speed of the Z-ring during the constriction period will be measured using the superresolution imaging technique. This speed will then be compared with the calculated speed based on single-molecule measurements of the disassembly rate and density change of the Z-ring. The role of GTP hydrolysis in Z-ring contraction will also be examined using an FtsZ GTPase mutant. These experiments, combined with the structural model that will be established in Aim 1, will provide important insight into the molecular mechanism of Z-ring contraction. Successful completion of the proposed work will provide: (1) a high-resolution Z- ring structural model;(2) a mechanism of how this structure contracts and (3) a set of innovative in vivo single-molecule assays.

Public Health Relevance

The goal of this study is to understand how bacterial cells divide using a central supramolecular assembly, the Z-ring. As the Z-ring is essential for survival and conserved across the bacterial kingdom, a better understanding will promote more effective development of new antibiotics to combat infectious diseases caused by pathogenic bacteria.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
1R01GM086447-01A2
Application #
8108519
Study Section
Macromolecular Structure and Function C Study Section (MSFC)
Program Officer
Deatherage, James F
Project Start
2011-04-01
Project End
2016-03-31
Budget Start
2011-04-01
Budget End
2012-03-31
Support Year
1
Fiscal Year
2011
Total Cost
$352,600
Indirect Cost
Name
Johns Hopkins University
Department
Physiology
Type
Schools of Medicine
DUNS #
001910777
City
Baltimore
State
MD
Country
United States
Zip Code
21218
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Coltharp, Carla; Xiao, Jie (2017) Beyond force generation: Why is a dynamic ring of FtsZ polymers essential for bacterial cytokinesis? Bioessays 39:1-11
Buss, Jackson A; Peters, Nick T; Xiao, Jie et al. (2017) ZapA and ZapB form an FtsZ-independent structure at midcell. Mol Microbiol 104:652-663
Woldemeskel, Selamawit Abi; McQuillen, Ryan; Hessel, Alex M et al. (2017) A conserved coiled-coil protein pair focuses the cytokinetic Z-ring in Caulobacter crescentus. Mol Microbiol 105:721-740
Xiao, Jie; DufrĂȘne, Yves F (2016) Optical and force nanoscopy in microbiology. Nat Microbiol 1:16186
Xiao, Jie; Goley, Erin D (2016) Redefining the roles of the FtsZ-ring in bacterial cytokinesis. Curr Opin Microbiol 34:90-96
Lyu, Zhixin; Coltharp, Carla; Yang, Xinxing et al. (2016) Influence of FtsZ GTPase activity and concentration on nanoscale Z-ring structure in vivo revealed by three-dimensional Superresolution imaging. Biopolymers 105:725-34
Coltharp, Carla; Buss, Jackson; Plumer, Trevor M et al. (2016) Defining the rate-limiting processes of bacterial cytokinesis. Proc Natl Acad Sci U S A 113:E1044-53
Buss, Jackson; Coltharp, Carla; Shtengel, Gleb et al. (2015) A multi-layered protein network stabilizes the Escherichia coli FtsZ-ring and modulates constriction dynamics. PLoS Genet 11:e1005128
Coltharp, Carla; Yang, Xinxing; Xiao, Jie (2014) Quantitative analysis of single-molecule superresolution images. Curr Opin Struct Biol 28:112-21

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