DYNAMICS OF Z-RING FORMATION IN LIPOSOMES

Cell division in bacteria is a highly controlled and regulated process. FtsZ, a bacterial cytoskeletal protein, forms a ring-like structure known as the Z-ring and recruits more than a dozen other cell division proteins. The Min system oscillates between the poles and inhibits the Z-ring formation at the poles by perturbing FtsZ assembly. This leads to an increase in the FtsZ concentration at the mid-cell and helps in Z-ring positioning. MinC, the effector protein, interferes with Z-ring formation through two different mechanisms mediated by its two domains with the help of MinD. However, the mechanism by which MinD triggers MinC activity is not yet known. We showed that MinD directly interacts with FtsZ with an affinity stronger than the reported MinC–FtsZ interaction. We determined the MinD-binding site of FtsZ using computational, mutational and biochemical analyses. Our study showed that MinD binds to the H10 helix of FtsZ. Single-point mutations at the charged residues in the H10 helix resulted in a decrease in the FtsZ affinity towards MinD. Based on our findings, we propose a novel model for MinCD–FtsZ interaction, where MinD through its direct interaction with FtsZ would trigger MinC activity to inhibit FtsZ functions.

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Noc Corrals Migration of FtsZ Protofilaments during Cytokinesis in Bacillus subtilis

mBio ◽

10.1128/mbio.02964-20 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Yuanchen Yu ◽

Jinsheng Zhou ◽

Frederico J. Gueiros-Filho ◽

Daniel B. Kearns ◽

Stephen C. Jacobson

Keyword(s):

Bacillus Subtilis ◽

Cell Division ◽

Fluorescence Microscopy ◽

Control Cell ◽

Time Lapse ◽

Ring Formation ◽

Microfluidic Channels ◽

Content Type ◽

The Future ◽

Z Ring

ABSTRACT Bacteria that divide by binary fission form FtsZ rings at the geometric midpoint of the cell between the bulk of the replicated nucleoids. In Bacillus subtilis, the DNA- and membrane-binding Noc protein is thought to participate in nucleoid occlusion by preventing FtsZ rings from forming over the chromosome. To explore the role of Noc, we used time-lapse fluorescence microscopy to monitor FtsZ and the nucleoid of cells growing in microfluidic channels. Our data show that Noc does not prevent de novo FtsZ ring formation over the chromosome nor does Noc control cell division site selection. Instead, Noc corrals FtsZ at the cytokinetic ring and reduces migration of protofilaments over the chromosome to the future site of cell division. Moreover, we show that FtsZ protofilaments travel due to a local reduction in ZapA association, and the diffuse FtsZ rings observed in the Noc mutant can be suppressed by ZapA overexpression. Thus, Noc sterically hinders FtsZ migration away from the Z-ring during cytokinesis and retains FtsZ at the postdivisional polar site for full disassembly by the Min system. IMPORTANCE In bacteria, a condensed structure of FtsZ (Z-ring) recruits cell division machinery at the midcell, and Z-ring formation is discouraged over the chromosome by a poorly understood phenomenon called nucleoid occlusion. In B. subtilis, nucleoid occlusion has been reported to be mediated, at least in part, by the DNA-membrane bridging protein, Noc. Using time-lapse fluorescence microscopy of cells growing in microchannels, we show that Noc neither protects the chromosome from proximal Z-ring formation nor determines the future site of cell division. Rather, Noc plays a corralling role by preventing protofilaments from leaving a Z-ring undergoing cytokinesis and traveling over the nucleoid.

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Transient Membrane-Linked FtsZ Assemblies Precede Z-Ring Formation in Escherichia Coli

SSRN Electronic Journal ◽

10.2139/ssrn.3396810 ◽

2019 ◽

Author(s):

Bryant E. Walker ◽

Jaana Männik ◽

Jaan Mannik

Keyword(s):

Escherichia Coli ◽

Ring Formation ◽

Z Ring

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Studying Z-ring formation following nucleoid partitioning in escherichia coli by microscopy flow-cytometry and machine learning

Advances in Robotics & Automation ◽

10.4172/2168-9695-c4-024 ◽

2018 ◽

Vol 07 ◽

Author(s):

Bilena Almeida ◽

Vatsala Chauhan ◽

Andre S Ribeiro

Keyword(s):

Machine Learning ◽

Escherichia Coli ◽

Flow Cytometry ◽

Ring Formation ◽

Z Ring

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Transcription Regulation of ezrA and Its Effect on Cell Division of Bacillus subtilis

Journal of Bacteriology ◽

10.1128/jb.186.17.5926-5932.2004 ◽

2004 ◽

Vol 186 (17) ◽

pp. 5926-5932 ◽

Cited By ~ 11

Author(s):

Kuei-Min Chung ◽

Hsin-Hsien Hsu ◽

Suresh Govindan ◽

Ban-Yang Chang

Keyword(s):

Bacillus Subtilis ◽

Cell Division ◽

Critical Concentration ◽

In Vitro Transcription ◽

Ring Formation ◽

Negative Regulator ◽

Cell Length ◽

Intracellular Level ◽

Z Ring

ABSTRACT The EzrA protein of Bacillus subtilis is a negative regulator for FtsZ (Z)-ring formation. It is able to modulate the frequency and position of Z-ring formation during cell division. The loss of this protein results in cells with multiple Z rings located at polar as well as medial sites; it also lowers the critical concentration of FtsZ required for ring formation (P. A. Levin, I. G. Kurster, and A. D. Grossman, Proc. Natl. Acad. Sci. USA 96:9642-9647, 1999). We have studied the regulation of ezrA expression during the growth of B. subtilis and its effects on the intracellular level of EzrA as well as the cell length of B. subtilis. With the aid of promoter probing, primer extension, in vitro transcription, and Western blotting analyses, two overlapping σA-type promoters, P1 and P2, located about 100 bp upstream of the initiation codon of ezrA, have been identified. P1, supposed to be an extended −10 promoter, was responsible for most of the ezrA expression during the growth of B. subtilis. Disruption of this promoter reduced the intracellular level of EzrA very significantly compared with disruption of P2. Moreover, deletion of both promoters completely abolished EzrA in B. subtilis. More importantly, the cell length and percentage of filamentous cells of B. subtilis were significantly increased by disruption of the promoter(s). Thus, EzrA is required for efficient cell division during the growth of B. subtilis, despite serving as a negative regulator for Z-ring formation.

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Trapping of a Spiral-Like Intermediate of the Bacterial Cytokinetic Protein FtsZ

Journal of Bacteriology ◽

10.1128/jb.188.5.1680-1690.2006 ◽

2006 ◽

Vol 188 (5) ◽

pp. 1680-1690 ◽

Cited By ~ 35

Author(s):

Katherine A. Michie ◽

Leigh G. Monahan ◽

Peter L. Beech ◽

Elizabeth J. Harry

Keyword(s):

Ring Formation ◽

Temperature Sensitive ◽

Permissive Temperature ◽

Nonpermissive Temperature ◽

Bacterial Cell Division ◽

Temporal Regulation ◽

Division Site ◽

Spiral Form ◽

Z Ring

ABSTRACT The earliest stage in bacterial cell division is the formation of a ring, composed of the tubulin-like protein FtsZ, at the division site. Tight spatial and temporal regulation of Z-ring formation is required to ensure that division occurs precisely at midcell between two replicated chromosomes. However, the mechanism of Z-ring formation and its regulation in vivo remain unresolved. Here we identify the defect of an interesting temperature-sensitive ftsZ mutant (ts1) of Bacillus subtilis. At the nonpermissive temperature, the mutant protein, FtsZ(Ts1), assembles into spiral-like structures between chromosomes. When shifted back down to the permissive temperature, functional Z rings form and division resumes. Our observations support a model in which Z-ring formation at the division site arises from reorganization of a long cytoskeletal spiral form of FtsZ and suggest that the FtsZ(Ts1) protein is captured as a shorter spiral-forming intermediate that is unable to complete this reorganization step. The ts1 mutant is likely to be very valuable in revealing how FtsZ assembles into a ring and how this occurs precisely at the division site.

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