51
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Ye W, Celiksoy S, Jakab A, Khmelinskaia A, Heermann T, Raso A, Wegner SV, Rivas G, Schwille P, Ahijado-Guzmán R, Sönnichsen C. Plasmonic Nanosensors Reveal a Height Dependence of MinDE Protein Oscillations on Membrane Features. J Am Chem Soc 2018; 140:17901-17906. [PMID: 30481454 DOI: 10.1021/jacs.8b07759] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Single-particle plasmon spectroscopy has become a standard technique to detect and quantify the presence of unlabeled macromolecules. Here, we extend this method to determine their exact distance from the plasmon sensors with sub-nanometer resolution by systematically varying the sensing range into the surrounding by adjusting the size of the plasmonic nanoparticles. We improved current single-particle plasmon spectroscopy to record continuously for hours the scattering spectra of thousands of nanoparticles of different sizes simultaneously with 1.8 s time resolution. We apply this technique to study the interaction dynamics of bacterial Min proteins with supported lipid membranes of different composition. Our experiments reveal a surprisingly flexible operating mode of the Min proteins: In the presence of cardiolipin and membrane curvature induced by nanoparticles, the protein oscillation occurs on top of a stationary MinD patch. Our results reveal the need to consider membrane composition and local curvature as important parameters to quantitatively understand the Min protein system and could be extrapolated to other macromolecular systems. Our label-free method is generally easily implementable and well suited to measure distances of interacting biological macromolecules.
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Affiliation(s)
- Weixiang Ye
- Institute of Physical Chemistry , University of Mainz , Duesbergweg 10-14 , 55128 Mainz , Germany.,Graduate School of Excellence Materials Science in Mainz (MAINZ) , Staudinger Weg 9 , 55128 Mainz , Germany
| | - Sirin Celiksoy
- Institute of Physical Chemistry , University of Mainz , Duesbergweg 10-14 , 55128 Mainz , Germany
| | - Arpad Jakab
- Institute of Physical Chemistry , University of Mainz , Duesbergweg 10-14 , 55128 Mainz , Germany
| | - Alena Khmelinskaia
- Department of Cellular and Molecular Biophysics , Max Planck Institute of Biochemistry , Am Klopferspitz 18 , 82152 Martinsried , Germany
| | - Tamara Heermann
- Department of Cellular and Molecular Biophysics , Max Planck Institute of Biochemistry , Am Klopferspitz 18 , 82152 Martinsried , Germany
| | - Ana Raso
- Department of Cellular and Molecular Biophysics , Max Planck Institute of Biochemistry , Am Klopferspitz 18 , 82152 Martinsried , Germany.,Centro de Investigaciones Biológicas-CSIC , c/Ramiro de Maeztu 9 , 28040 Madrid , Spain
| | - Seraphine V Wegner
- Max-Planck Institute for Polymer Research , Ackermannweg 10 , 55128 Mainz , Germany
| | - Germán Rivas
- Centro de Investigaciones Biológicas-CSIC , c/Ramiro de Maeztu 9 , 28040 Madrid , Spain
| | - Petra Schwille
- Department of Cellular and Molecular Biophysics , Max Planck Institute of Biochemistry , Am Klopferspitz 18 , 82152 Martinsried , Germany
| | - Rubén Ahijado-Guzmán
- Institute of Physical Chemistry , University of Mainz , Duesbergweg 10-14 , 55128 Mainz , Germany
| | - Carsten Sönnichsen
- Institute of Physical Chemistry , University of Mainz , Duesbergweg 10-14 , 55128 Mainz , Germany
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52
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Beppu K, Izri Z, Maeda YT, Sakamoto R. Geometric Effect for Biological Reactors and Biological Fluids. Bioengineering (Basel) 2018; 5:E110. [PMID: 30551608 PMCID: PMC6316181 DOI: 10.3390/bioengineering5040110] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 12/07/2018] [Accepted: 12/10/2018] [Indexed: 01/21/2023] Open
Abstract
As expressed "God made the bulk; the surface was invented by the devil" by W. Pauli, the surface has remarkable properties because broken symmetry in surface alters the material properties. In biological systems, the smallest functional and structural unit, which has a functional bulk space enclosed by a thin interface, is a cell. Cells contain inner cytosolic soup in which genetic information stored in DNA can be expressed through transcription (TX) and translation (TL). The exploration of cell-sized confinement has been recently investigated by using micron-scale droplets and microfluidic devices. In the first part of this review article, we describe recent developments of cell-free bioreactors where bacterial TX-TL machinery and DNA are encapsulated in these cell-sized compartments. Since synthetic biology and microfluidics meet toward the bottom-up assembly of cell-free bioreactors, the interplay between cellular geometry and TX-TL advances better control of biological structure and dynamics in vitro system. Furthermore, biological systems that show self-organization in confined space are not limited to a single cell, but are also involved in the collective behavior of motile cells, named active matter. In the second part, we describe recent studies where collectively ordered patterns of active matter, from bacterial suspensions to active cytoskeleton, are self-organized. Since geometry and topology are vital concepts to understand the ordered phase of active matter, a microfluidic device with designed compartments allows one to explore geometric principles behind self-organization across the molecular scale to cellular scale. Finally, we discuss the future perspectives of a microfluidic approach to explore the further understanding of biological systems from geometric and topological aspects.
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Affiliation(s)
- Kazusa Beppu
- Department of Physics, Kyushu University, Fukuoka 819-0395, Japan.
| | - Ziane Izri
- Department of Physics, Kyushu University, Fukuoka 819-0395, Japan.
| | - Yusuke T Maeda
- Department of Physics, Kyushu University, Fukuoka 819-0395, Japan.
| | - Ryota Sakamoto
- Department of Physics, Kyushu University, Fukuoka 819-0395, Japan.
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53
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Dewachter L, Verstraeten N, Fauvart M, Michiels J. An integrative view of cell cycle control in Escherichia coli. FEMS Microbiol Rev 2018; 42:116-136. [PMID: 29365084 DOI: 10.1093/femsre/fuy005] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 01/19/2018] [Indexed: 11/14/2022] Open
Abstract
Bacterial proliferation depends on the cells' capability to proceed through consecutive rounds of the cell cycle. The cell cycle consists of a series of events during which cells grow, copy their genome, partition the duplicated DNA into different cell halves and, ultimately, divide to produce two newly formed daughter cells. Cell cycle control is of the utmost importance to maintain the correct order of events and safeguard the integrity of the cell and its genomic information. This review covers insights into the regulation of individual key cell cycle events in Escherichia coli. The control of initiation of DNA replication, chromosome segregation and cell division is discussed. Furthermore, we highlight connections between these processes. Although detailed mechanistic insight into these connections is largely still emerging, it is clear that the different processes of the bacterial cell cycle are coordinated to one another. This careful coordination of events ensures that every daughter cell ends up with one complete and intact copy of the genome, which is vital for bacterial survival.
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Affiliation(s)
- Liselot Dewachter
- Centre of Microbial and Plant Genetics, KU Leuven-University of Leuven, B-3001 Leuven, Belgium.,VIB Center for Microbiology, B-3001 Leuven, Belgium
| | - Natalie Verstraeten
- Centre of Microbial and Plant Genetics, KU Leuven-University of Leuven, B-3001 Leuven, Belgium.,VIB Center for Microbiology, B-3001 Leuven, Belgium
| | - Maarten Fauvart
- Centre of Microbial and Plant Genetics, KU Leuven-University of Leuven, B-3001 Leuven, Belgium.,VIB Center for Microbiology, B-3001 Leuven, Belgium.,Department of Life Sciences and Imaging, Smart Electronics Unit, imec, B-3001 Leuven, Belgium
| | - Jan Michiels
- Centre of Microbial and Plant Genetics, KU Leuven-University of Leuven, B-3001 Leuven, Belgium.,VIB Center for Microbiology, B-3001 Leuven, Belgium
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54
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MacCready JS, Hakim P, Young EJ, Hu L, Liu J, Osteryoung KW, Vecchiarelli AG, Ducat DC. Protein gradients on the nucleoid position the carbon-fixing organelles of cyanobacteria. eLife 2018; 7:39723. [PMID: 30520729 PMCID: PMC6328274 DOI: 10.7554/elife.39723] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 11/19/2018] [Indexed: 12/25/2022] Open
Abstract
Carboxysomes are protein-based bacterial organelles encapsulating key enzymes of the Calvin-Benson-Bassham cycle. Previous work has implicated a ParA-like protein (hereafter McdA) as important for spatially organizing carboxysomes along the longitudinal axis of the model cyanobacterium Synechococcus elongatus PCC 7942. Yet, how self-organization of McdA emerges and contributes to carboxysome positioning is unknown. Here, we identify a small protein, termed McdB that localizes to carboxysomes and drives emergent oscillatory patterning of McdA on the nucleoid. Our results demonstrate that McdB directly stimulates McdA ATPase activity and its release from DNA, driving carboxysome-dependent depletion of McdA locally on the nucleoid and promoting directed motion of carboxysomes towards increased concentrations of McdA. We propose that McdA and McdB are a previously unknown class of self-organizing proteins that utilize a Brownian-ratchet mechanism to position carboxysomes in cyanobacteria, rather than a cytoskeletal system. These results have broader implications for understanding spatial organization of protein mega-complexes and organelles in bacteria. Cyanobacteria are tiny organisms that can harness the energy of the sun to power their cells. Many of the tools required for this complex photosynthetic process are packaged into small compartments inside the cell, the carboxysomes. In Synechococcus elongatus, a cyanobacterium that is shaped like a rod, the carboxysomes are positioned at regular intervals along the length of the cell. This ensures that, when the bacterium splits itself in half to reproduce, both daughter cells have the same number of carboxysomes. Researchers know that, in S. elongatus, a protein called McdA can oscillate from one end of the cell to the other. This protein is responsible for the carboxysomes being in the right place, and some scientists believe that it helps to create an internal skeleton that anchors and drags the compartments into position. Here, MacCready et al. propose another mechanism and, by combining various approaches, identify a new partner for McdA. This protein, called McdB, is present on the carboxysomes. McdB also binds to McdA, which itself attaches to the nucleoid – the region in the cell that contains the DNA. McdB forces McdA to release itself from DNA, causing the protein to reposition itself along the nucleoid. Because McdB attaches to McdA, the carboxysomes then follow suit, constantly seeking the highest concentrations of McdA bound to nearby DNA. Instead of relying on a cellular skeleton, these two proteins can organize themselves on their own using the nucleoid as a scaffold; in turn, they distribute carboxysomes evenly along the length of a cell. Plants also obtain their energy from the sun via photosynthesis, but they do not carry carboxysomes. Scientists have tried to introduce these compartments inside plant cells, hoping that it could generate crops with higher yields. Knowing how carboxysomes are organized so they can be passed down from one generation to the next could be important for these experiments.
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Affiliation(s)
- Joshua S MacCready
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, United States
| | - Pusparanee Hakim
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Michigan, United States
| | - Eric J Young
- Department of Biochemistry, Michigan State University, East Lansing, United States
| | - Longhua Hu
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, United States
| | - Jian Liu
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, United States
| | | | - Anthony G Vecchiarelli
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Michigan, United States
| | - Daniel C Ducat
- Department of Biochemistry, Michigan State University, East Lansing, United States.,MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, United States
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55
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The Min Oscillator Defines Sites of Asymmetric Cell Division in Cyanobacteria during Stress Recovery. Cell Syst 2018; 7:471-481.e6. [PMID: 30414921 DOI: 10.1016/j.cels.2018.10.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 09/04/2018] [Accepted: 10/15/2018] [Indexed: 11/20/2022]
Abstract
When resources are abundant, many rod-shaped bacteria reproduce through precise, symmetric divisions. However, realistic environments entail fluctuations between restrictive and permissive growth conditions. Here, we use time-lapse microscopy to study the division of the cyanobacterium Synechococcus elongatus as illumination intensity varies. We find that dim conditions produce elongated cells whose divisions follow a simple rule: cells shorter than ∼8 μm divide symmetrically, but above this length divisions become asymmetric, typically producing a short ∼3-μm daughter. We show that this division strategy is implemented by the Min system, which generates multi-node patterns and traveling waves in longer cells that favor the production of a short daughter. Mathematical modeling reveals that the feedback loops that create oscillatory Min patterns are needed to implement these generalized cell division rules. Thus, the Min system, which enforces symmetric divisions in short cells, acts to strongly suppress mid-cell divisions when S. elongatus cells are long.
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56
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Glock P, Schwille P. Switching protein patterns on membranes. Curr Opin Colloid Interface Sci 2018. [DOI: 10.1016/j.cocis.2018.10.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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57
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Sundararajan K, Vecchiarelli A, Mizuuchi K, Goley ED. Species- and C-terminal linker-dependent variations in the dynamic behavior of FtsZ on membranes in vitro. Mol Microbiol 2018; 110:47-63. [PMID: 30010220 DOI: 10.1111/mmi.14081] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/17/2018] [Indexed: 10/28/2022]
Abstract
Bacterial cell division requires the assembly of FtsZ protofilaments into a dynamic structure called the 'Z-ring'. The Z-ring recruits the division machinery and directs local cell wall remodeling for constriction. The organization and dynamics of protofilaments within the Z-ring coordinate local cell wall synthesis during cell constriction, but their regulation is largely unknown. The disordered C-terminal linker (CTL) region of Caulobacter crescentus FtsZ (CcFtsZ) regulates polymer structure and turnover in solution in vitro, and regulates Z-ring structure and activity of cell wall enzymes in vivo. To investigate the contributions of the CTL to the polymerization properties of FtsZ on its physiological platform, the cell membrane, we reconstituted CcFtsZ polymerization on supported lipid bilayers (SLB) and visualized polymer dynamics and structure using total internal reflection fluorescence microscopy. Unlike Escherichia coli FtsZ protofilaments that organized into large, bundled patterns, CcFtsZ protofilaments assembled into small, dynamic clusters on SLBs. Moreover, CcFtsZ lacking its CTL formed large networks of straight filament bundles that underwent slower turnover than the dynamic clusters of wildtype FtsZ. Our in vitro characterization provides novel insights into species- and CTL-dependent differences between FtsZ assembly properties that are relevant to Z-ring assembly and function on membranes in vivo.
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Affiliation(s)
- Kousik Sundararajan
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Anthony Vecchiarelli
- Molecular, Cellular, and Developmental Biology, University of Michigan College of Literature Science and the Arts, Ann Arbor, MI, 48109, USA
| | - Kiyoshi Mizuuchi
- Laboratory of Molecular Biology, National Institute of Diabetes, and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20814, USA
| | - Erin D Goley
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
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58
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Ke L, Cao LJ, Geng MT, Wang CC, Yao Y, Xiao Y, Huang W, Li RM, Min Y, Guo JC. Identification and expression analysis of MinD gene involved in plastid division in cassava. Biosci Biotechnol Biochem 2018; 83:76-86. [PMID: 30286695 DOI: 10.1080/09168451.2018.1520075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Cassava is a tropical crop known for its starchy root and excellent properties. Considering that starch biosynthesis in the amyloplast is affected by its division, it appears conceivable that the regulation of plastid division plays an important role in starch accumulation. As a member of the Min system genes, MinD participated in the spatial regulation of the position of the plastid division site.In our studies, sequence analysis and phylogenetic analysis showed that MeMinD has been highly conserved during the evolutionary process. Subcellular localisation indicated that MeMinD carries a chloroplast transit peptide and was localised in the chloroplast. Overexpression of MeMinD resulted in division site misplacement and filamentous formation in E. coli, indicating that MeMinD protein was functional across species. MeMinD exhibited different spatial and temporal expression patterns which was highly expressed in the source compared to that in the sink organ.
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Affiliation(s)
- Lei Ke
- a Hainan Key Laboratory for Sustainable Utilisation of Tropical Bioresource , Institute of Tropical Agriculture and Forestry, Hainan University , Haikou , China
| | - Liang-Jing Cao
- b Institute of Tropical Bioscience and Biotechnology , Chinese Academy of Tropical Agricultural Sciences , Haikou , China
| | - Meng-Ting Geng
- a Hainan Key Laboratory for Sustainable Utilisation of Tropical Bioresource , Institute of Tropical Agriculture and Forestry, Hainan University , Haikou , China
| | - Cong-Cong Wang
- a Hainan Key Laboratory for Sustainable Utilisation of Tropical Bioresource , Institute of Tropical Agriculture and Forestry, Hainan University , Haikou , China
| | - Yuan Yao
- b Institute of Tropical Bioscience and Biotechnology , Chinese Academy of Tropical Agricultural Sciences , Haikou , China
| | - Yu Xiao
- a Hainan Key Laboratory for Sustainable Utilisation of Tropical Bioresource , Institute of Tropical Agriculture and Forestry, Hainan University , Haikou , China
| | - Wu Huang
- a Hainan Key Laboratory for Sustainable Utilisation of Tropical Bioresource , Institute of Tropical Agriculture and Forestry, Hainan University , Haikou , China
| | - Rui-Mei Li
- b Institute of Tropical Bioscience and Biotechnology , Chinese Academy of Tropical Agricultural Sciences , Haikou , China
| | - Yi Min
- a Hainan Key Laboratory for Sustainable Utilisation of Tropical Bioresource , Institute of Tropical Agriculture and Forestry, Hainan University , Haikou , China
| | - Jian-Chun Guo
- b Institute of Tropical Bioscience and Biotechnology , Chinese Academy of Tropical Agricultural Sciences , Haikou , China
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59
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Blair KM, Mears KS, Taylor JA, Fero J, Jones LA, Gafken PR, Whitney JC, Salama NR. The Helicobacter pylori cell shape promoting protein Csd5 interacts with the cell wall, MurF, and the bacterial cytoskeleton. Mol Microbiol 2018; 110:114-127. [PMID: 30039535 DOI: 10.1111/mmi.14087] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/20/2018] [Indexed: 12/17/2022]
Abstract
Chronic infection with Helicobacter pylori can lead to the development of gastric ulcers and stomach cancers. The helical cell shape of H. pylori promotes stomach colonization. Screens for loss of helical shape have identified several periplasmic peptidoglycan (PG) hydrolases and non-enzymatic putative scaffolding proteins, including Csd5. Both over and under expression of the PG hydrolases perturb helical shape, but the mechanism used to coordinate and localize their enzymatic activities is not known. Using immunoprecipitation and mass spectrometry we identified Csd5 interactions with cytosolic proteins CcmA, a bactofilin required for helical shape, and MurF, a PG precursor synthase, as well as the inner membrane spanning ATP synthase. A combination of Csd5 domain deletions, point mutations, and transmembrane domain chimeras revealed that the N-terminal transmembrane domain promotes MurF, CcmA, and ATP synthase interactions, while the C-terminal SH3 domain mediates PG binding. We conclude that Csd5 promotes helical shape as part of a membrane associated, multi-protein shape complex that includes interactions with the periplasmic cell wall, a PG precursor synthesis enzyme, the bacterial cytoskeleton, and ATP synthase.
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Affiliation(s)
- Kris M Blair
- Division of Human Biology, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave, Seattle, WA, 98109, USA.,Molecular and Cellular Biology Ph.D. Program, University of Washington, 1959 NE Pacific Street, HSB T-466, Box 357275, Seattle, WA, 98195-7275, USA
| | - Kevin S Mears
- Division of Human Biology, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave, Seattle, WA, 98109, USA
| | - Jennifer A Taylor
- Division of Human Biology, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave, Seattle, WA, 98109, USA.,Department of Microbiology, University of Washington, 1705 NE Pacific St., HSB K-343, Box 357735, Seattle, WA, 98195-7735, USA
| | - Jutta Fero
- Division of Human Biology, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave, Seattle, WA, 98109, USA
| | - Lisa A Jones
- Proteomics Facility, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N., DE-352, Seattle, WA, 98109-1024, USA
| | - Philip R Gafken
- Proteomics Facility, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N., DE-352, Seattle, WA, 98109-1024, USA
| | - John C Whitney
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, L8S 4K1, Canada
| | - Nina R Salama
- Division of Human Biology, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave, Seattle, WA, 98109, USA
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60
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Abstract
Bacteria have the ability to produce minicells, or small spherical versions of themselves that lack chromosomal DNA and are unable to replicate. A minicell can constitute as much as 20% of the cell’s volume. Although molecular biology and biotechnology have used minicells as laboratory tools for several decades, it is still puzzling that bacteria should produce such costly but potentially nonfunctional structures. Here, we show that bacteria gain a benefit by producing minicells and using them as a mechanism to eliminate damaged or oxidated proteins. The elimination allows the bacteria to tolerate higher levels of stress, such as increasing levels of streptomycin. If this mechanism extends from streptomycin to other antibiotics, minicell production could be an overlooked pathway that bacteria are using to resist antimicrobials. Many bacteria produce small, spherical minicells that lack chromosomal DNA and therefore are unable to proliferate. Although minicells have been used extensively by researchers as a molecular tool, nothing is known about why bacteria produce them. Here, we show that minicells help Escherichia coli cells to rid themselves of damaged proteins induced by antibiotic stress. By comparing the survival and growth rates of wild-type strains with the E. coliΔminC mutant, which produces excess minicells, we found that the mutant was more resistant to streptomycin. To determine the effects of producing minicells at the single-cell level, we also tracked the growth of ΔminC lineages by microscopy. We were able to show that the mutant increased the production of minicells in response to a higher level of the antibiotic. When we compared two sister cells, in which one produced minicells and the other did not, the daughters of the former had a shorter doubling time at this higher antibiotic level. Additionally, we found that minicells were more likely produced at the mother’s old pole, which is known to accumulate more aggregates. More importantly, by using a fluorescent IbpA chaperone to tag damage aggregates, we found that polar aggregates were contained by and ejected with the minicells produced by the mother bacterium. These results demonstrate for the first time the benefit to bacteria for producing minicells. IMPORTANCE Bacteria have the ability to produce minicells, or small spherical versions of themselves that lack chromosomal DNA and are unable to replicate. A minicell can constitute as much as 20% of the cell’s volume. Although molecular biology and biotechnology have used minicells as laboratory tools for several decades, it is still puzzling that bacteria should produce such costly but potentially nonfunctional structures. Here, we show that bacteria gain a benefit by producing minicells and using them as a mechanism to eliminate damaged or oxidated proteins. The elimination allows the bacteria to tolerate higher levels of stress, such as increasing levels of streptomycin. If this mechanism extends from streptomycin to other antibiotics, minicell production could be an overlooked pathway that bacteria are using to resist antimicrobials.
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61
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MacCready JS, Vecchiarelli AG. In long bacterial cells, the Min system can act off-center. Mol Microbiol 2018; 109:268-272. [DOI: 10.1111/mmi.13995] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/25/2018] [Indexed: 11/29/2022]
Affiliation(s)
- Joshua S. MacCready
- Molecular, Cellular, and Developmental Biology; University of Michigan College of Literature Science and the Arts; Biological Sciences Building Ann Arbor MI USA
| | - Anthony G. Vecchiarelli
- Molecular, Cellular, and Developmental Biology; University of Michigan College of Literature Science and the Arts; Biological Sciences Building Ann Arbor MI USA
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62
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Effects of geometry and topography on Min-protein dynamics. PLoS One 2018; 13:e0203050. [PMID: 30161173 PMCID: PMC6117030 DOI: 10.1371/journal.pone.0203050] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 08/14/2018] [Indexed: 12/13/2022] Open
Abstract
In the rod-shaped bacterium Escherichia coli, the center is selected by the Min-proteins as the site of cell division. To this end, the proteins periodically translocate between the two cell poles, where they suppress assembly of the cell division machinery. Ample evidence notably obtained from in vitro reconstitution experiments suggests that the oscillatory pattern results from self-organization of the proteins MinD and MinE in presence of a membrane. A mechanism built on cooperative membrane attachment of MinD and persistent MinD removal from the membrane induced by MinE has been shown to be able to reproduce the observed Min-protein patterns in rod-shaped E. coli and on flat supported lipid bilayers. Here, we report our results of a numerical investigation of patterns generated by this mechanism in various geoemtries. Notably, we consider the dynamics on membrane patches of different forms, on topographically structured lipid bilayers, and in closed geometries of various shapes. We find that all previously described patterns can be reproduced by the mechanism. However, it requires different parameter sets for reproducing the patterns in closed and in open geometries.
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63
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Ramm B, Glock P, Schwille P. In Vitro Reconstitution of Self-Organizing Protein Patterns on Supported Lipid Bilayers. J Vis Exp 2018. [PMID: 30102292 PMCID: PMC6126581 DOI: 10.3791/58139] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Many aspects of the fundamental spatiotemporal organization of cells are governed by reaction-diffusion type systems. In vitro reconstitution of such systems allows for detailed studies of their underlying mechanisms which would not be feasible in vivo. Here, we provide a protocol for the in vitro reconstitution of the MinCDE system of Escherichia coli, which positions the cell division septum in the cell middle. The assay is designed to supply only the components necessary for self-organization, namely a membrane, the two proteins MinD and MinE and energy in the form of ATP. We therefore fabricate an open reaction chamber on a coverslip, on which a supported lipid bilayer is formed. The open design of the chamber allows for optimal preparation of the lipid bilayer and controlled manipulation of the bulk content. The two proteins, MinD and MinE, as well as ATP, are then added into the bulk volume above the membrane. Imaging is possible by many optical microscopies, as the design supports confocal, wide-field and TIRF microscopy alike. In a variation of the protocol, the lipid bilayer is formed on a patterned support, on cell-shaped PDMS microstructures, instead of glass. Lowering the bulk solution to the rim of these compartments encloses the reaction in a smaller compartment and provides boundaries that allow mimicking of in vivo oscillatory behavior. Taken together, we describe protocols to reconstitute the MinCDE system both with and without spatial confinement, allowing researchers to precisely control all aspects influencing pattern formation, such as concentration ranges and addition of other factors or proteins, and to systematically increase system complexity in a relatively simple experimental setup.
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Affiliation(s)
- Beatrice Ramm
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry
| | - Philipp Glock
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry
| | - Petra Schwille
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry;
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64
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MinE conformational switching confers robustness on self-organized Min protein patterns. Proc Natl Acad Sci U S A 2018; 115:4553-4558. [PMID: 29666276 PMCID: PMC5939084 DOI: 10.1073/pnas.1719801115] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Many fundamental cellular processes are spatially regulated by self-organized protein patterns, which are often based on nucleotide-binding proteins that switch their nucleotide state upon interaction with a second, activating protein. For reliable function, these protein patterns must be robust against parameter changes, although the basis for such robustness is generally elusive. Here we take a combined theoretical and experimental approach to the Escherichia coli Min system, a paradigmatic system for protein self-organization. By mathematical modeling and in vitro reconstitution of mutant proteins, we demonstrate that the robustness of pattern formation is dramatically enhanced by an interlinked functional switching of both proteins, rather than one. Such interlinked functional switching could be a generic means of obtaining robustness in biological pattern-forming systems. Protein patterning is vital for many fundamental cellular processes. This raises two intriguing questions: Can such intrinsically complex processes be reduced to certain core principles and, if so, what roles do the molecular details play in individual systems? A prototypical example for protein patterning is the bacterial Min system, in which self-organized pole-to-pole oscillations of MinCDE proteins guide the cell division machinery to midcell. These oscillations are based on cycling of the ATPase MinD and its activating protein MinE between the membrane and the cytoplasm. Recent biochemical evidence suggests that MinE undergoes a reversible, MinD-dependent conformational switch from a latent to a reactive state. However, the functional relevance of this switch for the Min network and pattern formation remains unclear. By combining mathematical modeling and in vitro reconstitution of mutant proteins, we dissect the two aspects of MinE’s switch, persistent membrane binding and a change in MinE’s affinity for MinD. Our study shows that the MinD-dependent change in MinE’s binding affinity for MinD is essential for patterns to emerge over a broad and physiological range of protein concentrations. Mechanistically, our results suggest that conformational switching of an ATPase-activating protein can lead to the spatial separation of its distinct functional states and thereby confer robustness on an intracellular protein network with vital roles in bacterial cell division.
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65
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Huang H, Wang P, Bian L, Osawa M, Erickson HP, Chen Y. The cell division protein MinD from Pseudomonas aeruginosa dominates the assembly of the MinC-MinD copolymers. J Biol Chem 2018; 293:7786-7795. [PMID: 29610277 DOI: 10.1074/jbc.ra117.001513] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2017] [Revised: 03/30/2018] [Indexed: 01/22/2023] Open
Abstract
Cell division of rod-shaped bacteria requires the Z ring, a ring of FtsZ filaments associated with the inner-membrane wall. The MinCDE proteins help localize the Z ring to the center of the Escherichia coli cell. MinC, which inhibits Z-ring assembly, is a passenger on MinD. Previous studies have shown that MinC-MinD from E. coli and Aquifex aeolicus assemble in vitro into extended filaments with a 1:1 stoichiometry. However, a recent study has raised questions about the function of the MinC-MinD copolymer in vivo, because its assembly appears to require a high concentration of these two proteins and has a long lag time, and its blockade does not affect in vivo activities. Here, we found that MinC and MinD from Pseudomonas aeruginosa coassemble into filaments with a 1:1 stoichiometry. We also found that the minimal concentration of ∼4 μm required for assembly applies only to MinD because above 4 μm MinD, even very low MinC concentrations sustained coassembly. As previously reported, the MinC-MinD coassembly exhibited a long lag of ∼100 s when initiated by ATP. Premixing MinD with ATP eliminated this lag, suggesting that it may be due to slow MinD dimerization following ATP activation. We also discovered that MinC-MinD copolymers quickly bound FtsZ filaments and formed huge bundles. Our results resolve previous questions about the low concentration of MinC and the lag time, insights that may inform future investigations into the exact role of the MinC-MinD copolymer in vivo.
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Affiliation(s)
- Haiyan Huang
- From the Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, Shaanxi, China 710069 and
| | - Ping Wang
- the Departments of Anesthesiology and
| | - Li Bian
- From the Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, Shaanxi, China 710069 and
| | - Masaki Osawa
- Cell Biology, Duke University Medical Center, Durham, North Carolina 27710
| | - Harold P Erickson
- Cell Biology, Duke University Medical Center, Durham, North Carolina 27710
| | - Yaodong Chen
- From the Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, Shaanxi, China 710069 and
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Mizuuchi K, Vecchiarelli AG. Mechanistic insights of the Min oscillator via cell-free reconstitution and imaging. Phys Biol 2018; 15:031001. [PMID: 29188788 DOI: 10.1088/1478-3975/aa9e5e] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The MinD and MinE proteins of Escherichia coli self-organize into a standing-wave oscillator on the membrane to help align division at mid-cell. When unleashed from cellular confines, MinD and MinE form a spectrum of patterns on artificial bilayers-static amoebas, traveling waves, traveling mushrooms, and bursts with standing-wave dynamics. We recently focused our cell-free studies on bursts because their dynamics recapitulate many features of Min oscillation observed in vivo. The data unveiled a patterning mechanism largely governed by MinE regulation of MinD interaction with membrane. We proposed that the MinD to MinE ratio on the membrane acts as a toggle switch between MinE-stimulated recruitment and release of MinD from the membrane. In this review, we summarize cell-free data on the Min system and expand upon a molecular mechanism that provides a biochemical explanation as to how these two 'simple' proteins can form the remarkable spectrum of patterns.
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Affiliation(s)
- Kiyoshi Mizuuchi
- Laboratory of Molecular Biology, National Institute of Diabetes, and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, United States of America
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Miyagi A, Ramm B, Schwille P, Scheuring S. High-Speed Atomic Force Microscopy Reveals the Inner Workings of the MinDE Protein Oscillator. NANO LETTERS 2018; 18:288-296. [PMID: 29210266 DOI: 10.1021/acs.nanolett.7b04128] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The MinDE protein system from E. coli has recently been identified as a minimal biological oscillator, based on two proteins only: The ATPase MinD and the ATPase activating protein MinE. In E. coli, the system works as the molecular ruler to place the divisome at midcell for cell division. Despite its compositional simplicity, the molecular mechanism leading to protein patterns and oscillations is still insufficiently understood. Here we used high-speed atomic force microscopy to analyze the mechanism of MinDE membrane association/dissociation dynamics on isolated membrane patches, down to the level of individual point oscillators. This nanoscale analysis shows that MinD association to and dissociation from the membrane are both highly cooperative but mechanistically different processes. We propose that they represent the two directions of a single allosteric switch leading to MinD filament formation and depolymerization. Association/dissociation are separated by rather long apparently silent periods. The membrane-associated period is characterized by MinD filament multivalent binding, avidity, while the dissociated period is defined by seeding of individual MinD. Analyzing association/dissociation kinetics with varying MinD and MinE concentrations and dependent on membrane patch size allowed us to disentangle the essential dynamic variables of the MinDE oscillation cycle.
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Affiliation(s)
- Atsushi Miyagi
- U1006 INSERM, Aix-Marseille Université, Parc Scientifique et Technologique de Luminy , 13009 Marseille, France
| | - Beatrice Ramm
- Max Planck Institute of Biochemistry , Am Klopferspitz 18, D-82152 Martinsried, Germany
| | - Petra Schwille
- Max Planck Institute of Biochemistry , Am Klopferspitz 18, D-82152 Martinsried, Germany
| | - Simon Scheuring
- U1006 INSERM, Aix-Marseille Université, Parc Scientifique et Technologique de Luminy , 13009 Marseille, France
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Ayed SH, Cloutier AD, McLeod LJ, Foo ACY, Damry AM, Goto NK. Dissecting the role of conformational change and membrane binding by the bacterial cell division regulator MinE in the stimulation of MinD ATPase activity. J Biol Chem 2017; 292:20732-20743. [PMID: 29066619 DOI: 10.1074/jbc.m117.805945] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 10/15/2017] [Indexed: 11/06/2022] Open
Abstract
The bacterial cell division regulators MinD and MinE together with the division inhibitor MinC localize to the membrane in concentrated zones undergoing coordinated pole-to-pole oscillation to help ensure that the cytokinetic division septum forms only at the mid-cell position. This dynamic localization is driven by MinD-catalyzed ATP hydrolysis, stimulated by interactions with MinE's anti-MinCD domain. This domain is buried in the 6-β-stranded MinE "closed" structure, but is liberated for interactions with MinD, giving rise to a 4-β-stranded "open" structure through an unknown mechanism. Here we show that MinE-membrane interactions induce a structural change into a state resembling the open conformation. However, MinE mutants lacking the MinE membrane-targeting sequence stimulated higher ATP hydrolysis rates than the full-length protein, indicating that binding to MinD is sufficient to trigger this conformational transition in MinE. In contrast, conformational change between the open and closed states did not affect stimulation of ATP hydrolysis rates in the absence of membrane binding, although the MinD-binding residue Ile-25 is critical for this conformational transition. We therefore propose an updated model where MinE is brought to the membrane through interactions with MinD. After stimulation of ATP hydrolysis, MinE remains bound to the membrane in a state that does not catalyze additional rounds of ATP hydrolysis. Although the molecular basis for this inhibited state is unknown, previous observations of higher-order MinE self-association may explain this inhibition. Overall, our findings have general implications for Min protein oscillation cycles, including those that regulate cell division in bacterial pathogens.
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Affiliation(s)
- Saud H Ayed
- From the Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Adam D Cloutier
- From the Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Laura J McLeod
- From the Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Alexander C Y Foo
- From the Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Adam M Damry
- From the Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Natalie K Goto
- From the Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
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69
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MinE conformational dynamics regulate membrane binding, MinD interaction, and Min oscillation. Proc Natl Acad Sci U S A 2017; 114:7497-7504. [PMID: 28652337 DOI: 10.1073/pnas.1707385114] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In Escherichia coli MinE induces MinC/MinD to oscillate between the ends of the cell, contributing to the precise placement of the Z ring at midcell. To do this, MinE undergoes a remarkable conformational change from a latent 6β-stranded form that diffuses in the cytoplasm to an active 4β-stranded form bound to the membrane and MinD. How this conformational switch occurs is not known. Here, using hydrogen-deuterium exchange coupled to mass spectrometry (HDX-MS) we rule out a model in which the two forms are in rapid equilibrium. Furthermore, HDX-MS revealed that a MinE mutant (D45A/V49A), previously shown to produce an aberrant oscillation and unable to assemble a MinE ring, is more rigid than WT MinE. This mutant has a defect in interaction with MinD, suggesting it has difficulty in switching to the active form. Analysis of intragenic suppressors of this mutant suggests it has difficulty in releasing the N-terminal membrane targeting sequences (MTS). These results indicate that the dynamic association of the MTS with the β-sheet is fine-tuned to balance MinE's need to sense MinD on the membrane with its need to diffuse in the cytoplasm, both of which are necessary for the oscillation. The results lead to models for MinE activation and MinE ring formation.
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Kretschmer S, Zieske K, Schwille P. Large-scale modulation of reconstituted Min protein patterns and gradients by defined mutations in MinE's membrane targeting sequence. PLoS One 2017. [PMID: 28622374 PMCID: PMC5473585 DOI: 10.1371/journal.pone.0179582] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The E. coli MinDE oscillator is a paradigm for protein self-organization and gradient formation. Previously, we reconstituted Min protein wave patterns on flat membranes as well as gradient-forming pole-to-pole oscillations in cell-shaped PDMS microcompartments. These oscillations appeared to require direct membrane interaction of the ATPase activating protein MinE. However, it remained unclear how exactly Min protein dynamics are regulated by MinE membrane binding. Here, we dissect the role of MinE’s membrane targeting sequence (MTS) by reconstituting various MinE mutants in 2D and 3D geometries. We demonstrate that the MTS defines the lower limit of the concentration-dependent wavelength of Min protein patterns while restraining MinE’s ability to stimulate MinD’s ATPase activity. Strikingly, a markedly reduced length scale—obtainable even by single mutations—is associated with a rich variety of multistable dynamic modes in cell-shaped compartments. This dramatic remodeling in response to biochemical changes reveals a remarkable trade-off between robustness and versatility of the Min oscillator.
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Affiliation(s)
- Simon Kretschmer
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany
- Graduate School of Quantitative Biosciences, Ludwig-Maximilians-Universität, München, Germany
| | - Katja Zieske
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Petra Schwille
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany
- * E-mail:
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Abstract
As discovered over the past 25 years, the cytoskeletons of bacteria and archaea are complex systems of proteins whose central components are dynamic cytomotive filaments. They perform roles in cell division, DNA partitioning, cell shape determination and the organisation of intracellular components. The protofilament structures and polymerisation activities of various actin-like, tubulin-like and ESCRT-like proteins of prokaryotes closely resemble their eukaryotic counterparts but show greater diversity. Their activities are modulated by a wide range of accessory proteins but these do not include homologues of the motor proteins that supplement filament dynamics to aid eukaryotic cell motility. Numerous other filamentous proteins, some related to eukaryotic IF-proteins/lamins and dynamins etc, seem to perform structural roles similar to those in eukaryotes.
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Affiliation(s)
- Linda A Amos
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
| | - Jan Löwe
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
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Abstract
Cytokinesis in E. coli is organized by a cytoskeletal element designated the Z ring. The Z ring is formed at midcell by the coalescence of FtsZ filaments tethered to the membrane by interaction of FtsZ's conserved C-terminal peptide (CCTP) with two membrane-associated proteins, FtsA and ZipA. Although interaction between an FtsZ monomer and either of these proteins is of low affinity, high affinity is achieved through avidity - polymerization linked CCTPs interacting with the membrane tethers. The placement of the Z ring at midcell is ensured by antagonists of FtsZ polymerization that are positioned within the cell and target FtsZ filaments through the CCTP. The placement of the ring is reinforced by a protein network that extends from the terminus (Ter) region of the chromosome to the Z ring. Once the Z ring is established, additional proteins are recruited through interaction with FtsA, to form the divisome. The assembled divisome is then activated by FtsN to carry out septal peptidoglycan synthesis, with a dynamic Z ring serving as a guide for septum formation. As the septum forms, the cell wall is split by spatially regulated hydrolases and the outer membrane invaginates in step with the aid of a transenvelope complex to yield progeny cells.
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Affiliation(s)
- Joe Lutkenhaus
- University of Kansas Medical Center, Kansas City, KS, USA.
| | - Shishen Du
- University of Kansas Medical Center, Kansas City, KS, USA
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MacCready JS, Schossau J, Osteryoung KW, Ducat DC. Robust Min-system oscillation in the presence of internal photosynthetic membranes in cyanobacteria. Mol Microbiol 2016; 103:483-503. [PMID: 27891682 DOI: 10.1111/mmi.13571] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/28/2016] [Indexed: 11/29/2022]
Abstract
The oscillatory Min system of Escherichia coli defines the cell division plane by regulating the site of FtsZ-ring formation and represents one of the best-understood examples of emergent protein self-organization in nature. The oscillatory patterns of the Min-system proteins MinC, MinD and MinE (MinCDE) are strongly dependent on the geometry of membranes they bind. Complex internal membranes within cyanobacteria could disrupt this self-organization by sterically occluding or sequestering MinCDE from the plasma membrane. Here, it was shown that the Min system in the cyanobacterium Synechococcus elongatus PCC 7942 oscillates from pole-to-pole despite the potential spatial constraints imposed by their extensive thylakoid network. Moreover, reaction-diffusion simulations predict robust oscillations in modeled cyanobacterial cells provided that thylakoid network permeability is maintained to facilitate diffusion, and suggest that Min proteins require preferential affinity for the plasma membrane over thylakoids to correctly position the FtsZ ring. Interestingly, in addition to oscillating, MinC exhibits a midcell localization dependent on MinD and the DivIVA-like protein Cdv3, indicating that two distinct pools of MinC are coordinated in S. elongatus. Our results provide the first direct evidence for Min oscillation outside of E. coli and have broader implications for Min-system function in bacteria and organelles with internal membrane systems.
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Affiliation(s)
- Joshua S MacCready
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824, USA
| | - Jory Schossau
- Department of Computer Science, Michigan State University, East Lansing, MI, 48824, USA
| | | | - Daniel C Ducat
- Department of Biochemistry, MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
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Caspi Y, Dekker C. Mapping out Min protein patterns in fully confined fluidic chambers. eLife 2016; 5. [PMID: 27885986 PMCID: PMC5217063 DOI: 10.7554/elife.19271] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 11/24/2016] [Indexed: 11/13/2022] Open
Abstract
The bacterial Min protein system provides a major model system for studying reaction-diffusion processes in biology. Here we present the first in vitro study of the Min system in fully confined three-dimensional chambers that are lithography-defined, lipid-bilayer coated and isolated through pressure valves. We identify three typical dynamical behaviors that occur dependent on the geometrical chamber parameters: pole-to-pole oscillations, spiral rotations, and traveling waves. We establish the geometrical selection rules and show that, surprisingly, Min-protein spiral rotations govern the larger part of the geometrical phase diagram. Confinement as well as an elevated temperature reduce the characteristic wavelength of the Min patterns, although even for confined chambers with a bacterial-level viscosity, the patterns retain a ~5 times larger wavelength than in vivo. Our results provide an essential experimental base for modeling of intracellular Min gradients in bacterial cell division as well as, more generally, for understanding pattern formation in reaction-diffusion systems. DOI:http://dx.doi.org/10.7554/eLife.19271.001 Some proteins can spontaneously organize themselves into ordered patterns within living cells. One widely studied pattern is made in a rod-shaped bacterium called Escherichia coli by a group of proteins called the Min proteins. The pattern formed by the Min proteins allows an E. coli cell to produce two equally sized daughter cells when it divides by ensuring that the division machinery correctly assembles at the center of the parent cell. These proteins move back and forth between the two ends of the parent cell so that the levels of Min proteins are highest at the ends and lowest in the middle. Since the Min proteins act to inhibit the assembly of the cell division machinery, this machinery only assembles in locations where the level of Min proteins is at its lowest, that is, at the middle of the cell. When Min proteins are purified and placed within an artificial compartment that contains a source of chemical energy and is covered by a membrane similar to the membranes that surround cells, they spontaneously form traveling waves on top of the membrane in many directions along to surface. It is not clear how these waves relate to the oscillations seen in E. coli. Caspi and Dekker now analyze the behavior of purified Min proteins inside chambers of various sizes that are fully enclosed by a membrane. The results show that in narrow chambers, Min proteins move back and forth (i.e. oscillate) from one side to the other. However, in wider containers the wave motion is more common. In containers of medium width the Min proteins rotate in a spiral fashion. Caspi and Dekker propose that the spiral rotations are the underlying pattern formed by Min proteins and that the back and forth motion is caused by spirals being cut short. In other words, if a spiral cannot form because the compartment is too small then the back and forth motion emerges. Similarly, Caspi and Dekker propose that the waves emerge in larger containers when multiple spirals come together. These findings suggest that the different patterns that Min proteins form in bacterial cells and artificial compartments arise from different underlying mechanisms. The next step will be to investigate other differences in how the patterns of Min proteins form in E. coli and in artificial compartments. DOI:http://dx.doi.org/10.7554/eLife.19271.002
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Affiliation(s)
- Yaron Caspi
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands
| | - Cees Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands
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Zieske K, Chwastek G, Schwille P. Protein Patterns and Oscillations on Lipid Monolayers and in Microdroplets. Angew Chem Int Ed Engl 2016; 55:13455-13459. [PMID: 27465495 PMCID: PMC5113663 DOI: 10.1002/anie.201606069] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Indexed: 11/25/2022]
Abstract
The Min proteins from E.coli position the bacterial cell-division machinery through pole-to-pole oscillations. In vitro, Min protein self-organization can be reconstituted in the presence of a lipid membrane as a catalytic surface. However, Min dynamics have so far not been reconstituted in fully membrane-enclosed volumes. Microdroplets interfaced by lipid monolayers were employed as a simple 3D mimic of cellular compartments to reconstitute Min protein oscillations. We demonstrate that lipid monolayers are sufficient to fulfil the catalytic role of the membrane and thus represent a facile platform to investigate Min protein regulated dynamics of the cell-division protein FtsZ-mts. In particular, we show that droplet containers reveal distinct Min oscillation modes, and reveal a dependence of FtsZ-mts structures on compartment size. Finally, co-reconstitution of Min proteins and FtsZ-mts in droplets yields antagonistic localization, thus demonstrating that droplets indeed support the analysis of complex bacterial self-organization in confined volumes.
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Affiliation(s)
- Katja Zieske
- Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
- Developmental Biology, Stanford University, Stanford, CA, 94305, USA
| | - Grzegorz Chwastek
- Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
| | - Petra Schwille
- Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany.
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