scholarly journals Residue 49 of AtMinD1 Plays a Key Role in the Guidance of Chloroplast Division by Regulating the ARC6-AtMinD1 Interaction

2021 ◽  
Vol 12 ◽  
Author(s):  
Yanhua Zhang ◽  
Xiaochen Zhang ◽  
Huanshuo Cui ◽  
Xinzhu Ma ◽  
Guipeng Hu ◽  
...  
Keyword(s):  
Direct Interaction ◽  
Asymmetric Division ◽  
Chloroplast Division ◽  
Chloroplast Envelope ◽  
Sufficient Evidence ◽  
Bacterial Cell Division ◽  
Terrestrial Plants ◽  
Chloroplast Transit Peptide ◽  
Punctate Structure ◽  
Division Site

Chloroplasts evolved from a free-living cyanobacterium through endosymbiosis. Similar to bacterial cell division, chloroplasts replicate by binary fission, which is controlled by the Minicell (Min) system through confining FtsZ ring formation at the mid-chloroplast division site. MinD, one of the most important members of the Min system, regulates the placement of the division site in plants and works cooperatively with MinE, ARC3, and MCD1. The loss of MinD function results in the asymmetric division of chloroplasts. In this study, we isolated one large dumbbell-shaped and asymmetric division chloroplast Arabidopsis mutant Chloroplast Division Mutant 75 (cdm75) that contains a missense mutation, changing the arginine at residue 49 to a histidine (R49H), and this mutant point is located in the N-terminal Conserved Terrestrial Sequence (NCTS) motif of AtMinD1, which is only typically found in terrestrial plants. This study provides sufficient evidence to prove that residues 1–49 of AtMinD1 are transferred into the chloroplast, and that the R49H mutation does not affect the function of the AtMinD1 chloroplast transit peptide. Subsequently, we showed that the point mutation of R49H could remove the punctate structure caused by residues 1–62 of the AtMinD1 sequence in the chloroplast, suggesting that the arginine in residue 49 (Arg49) is essential for localizing the punctate structure of AtMinD11–62 on the chloroplast envelope. Unexpectedly, we found that AtMinD1 could interact directly with ARC6, and that the R49H mutation could prevent not only the previously observed interaction between AtMinD1 and MCD1 but also the interaction between AtMinD1 and ARC6. Thus, we believe that these results show that the AtMinD1 NCTS motif is required for their protein interaction. Collectively, our results show that AtMinD1 can guide the placement of the division site to the mid chloroplast through its direct interaction with ARC6 and reveal the important role of AtMinD1 in regulating the AtMinD1-ARC6 interaction.

scholarly journals A homologue of the bacterial cell division site-determining factor MinD mediates placement of the chloroplast division apparatus

2000 ◽  
Vol 10 (9) ◽  
pp. 507-516 ◽  
Author(s):  
Kelly S. Colletti ◽  
Elizabeth A. Tattersall ◽  
Kevin A. Pyke ◽  
John E. Froelich ◽  
Kevin D. Stokes ◽  
...  
Keyword(s):  
Cell Division ◽  
Bacterial Cell ◽  
Chloroplast Division ◽  
Bacterial Cell Division ◽  
Division Site ◽  
Determining Factor

scholarly journals Cardiolipin-Containing Lipid Membranes Attract the Bacterial Cell Division Protein DivIVA

2021 ◽  
Vol 22 (15) ◽  
pp. 8350
Author(s):  
Naďa Labajová ◽  
Natalia Baranova ◽  
Miroslav Jurásek ◽  
Robert Vácha ◽  
Martin Loose ◽  
...  
Keyword(s):  
Cell Division ◽  
Lipid Bilayers ◽  
Bacterial Cell ◽  
Lipid Membranes ◽  
Model Organism ◽  
Active Role ◽  
Membrane Curvature ◽  
Bacterial Cell Division ◽  
Division Site ◽  
Clostridioides Difficile

DivIVA is a protein initially identified as a spatial regulator of cell division in the model organism Bacillus subtilis, but its homologues are present in many other Gram-positive bacteria, including Clostridia species. Besides its role as topological regulator of the Min system during bacterial cell division, DivIVA is involved in chromosome segregation during sporulation, genetic competence, and cell wall synthesis. DivIVA localizes to regions of high membrane curvature, such as the cell poles and cell division site, where it recruits distinct binding partners. Previously, it was suggested that negative curvature sensing is the main mechanism by which DivIVA binds to these specific regions. Here, we show that Clostridioides difficile DivIVA binds preferably to membranes containing negatively charged phospholipids, especially cardiolipin. Strikingly, we observed that upon binding, DivIVA modifies the lipid distribution and induces changes to lipid bilayers containing cardiolipin. Our observations indicate that DivIVA might play a more complex and so far unknown active role during the formation of the cell division septal membrane.

scholarly journals Digital Endpoints: Definition, Benefits, and Current Barriers in Accelerating Development and Adoption

2021 ◽  
pp. 216-223
Author(s):  
Matthew Landers ◽  
Ray Dorsey ◽  
Suchi Saria
Keyword(s):  
Health Care ◽  
Interdisciplinary Collaboration ◽  
Clinical Status ◽  
Direct Interaction ◽  
Living Environment ◽  
Assessment Tools ◽  
Rapid Expansion ◽  
Sufficient Evidence ◽  
Cooperative Effort ◽  
Remote Patient

The assessment of health and disease requires a set of criteria to define health status and progression. These health measures are referred to as “endpoints.” A “digital endpoint” is defined by its use of sensor-generated data often collected outside of a clinical setting such as in a patient’s free-living environment. Applicable sensors exist in an array of devices and can be applied in a diverse set of contexts. For example, a smartphone’s microphone might be used to diagnose or predict mild cognitive impairment due to Alzheimer’s disease or a wrist-worn activity monitor (such as those found in smartwatches) may be used to measure a drug’s effect on the nocturnal activity of patients with sickle cell disease. Digital endpoints are generating considerable excitement because they permit a more authentic assessment of the patient’s experience, reveal formerly untold realities of disease burden, and can cut drug discovery costs in half. However, before these benefits can be realized, effort must be applied not only to the technical creation of digital endpoints but also to the environment that allows for their development and application. The future of digital endpoints rests on meaningful interdisciplinary collaboration, sufficient evidence that digital endpoints can realize their promise, and the development of an ecosystem in which the vast quantities of data that digital endpoints generate can be analyzed. The fundamental nature of health care is changing. With coronavirus disease 2019 serving as a catalyst, there has been a rapid expansion of home care models, telehealth, and remote patient monitoring. The increasing adoption of these health-care innovations will expedite the requirement for a digital characterization of clinical status as current assessment tools often rely upon direct interaction with patients and thus are not fit for purpose to be administered remotely. With the ubiquity of relatively inexpensive sensors, digital endpoints are positioned to drive this consequential change. It is therefore not surprising that regulators, physicians, researchers, and consultants have each offered their assessment of these novel tools. However, as we further describe later, the broad adoption of digital endpoints will require a cooperative effort. In this article, we present an analysis of the current state of digital endpoints. We also attempt to unify the perspectives of the parties involved in the development and deployment of these tools. We conclude with an interdependent list of challenges that must be collaboratively addressed before these endpoints are widely adopted.

scholarly journals The Tol-Pal system is required for peptidoglycan-cleaving enzymes to complete bacterial cell division

2020 ◽  
Vol 117 (12) ◽  
pp. 6777-6783 ◽  
Author(s):  
Anastasiya A. Yakhnina ◽  
Thomas G. Bernhardt
Keyword(s):  
Cell Separation ◽  
Glycosyl Hydrolase ◽  
Gram Negative Bacteria ◽  
Bacterial Cell Division ◽  
General Role ◽  
E Coli ◽  
Division Site ◽  
Genetic Suppressors ◽  
Bacteria Inactivation ◽  
Mutant Cells

Tol-Pal is a multiprotein system present in the envelope of Gram-negative bacteria. Inactivation of this widely conserved machinery compromises the outer membrane (OM) layer of these organisms, resulting in hypersensitivity to many antibiotics. Mutants in thetol-pallocus fail to complete division and form cell chains. This phenotype along with the localization of Tol-Pal components to the cytokinetic ring inEscherichia colihas led to the proposal that the primary function of the system is to promote OM constriction during division. Accordingly, a poorly constricted OM is believed to link the cell chains formed upon Tol-Pal inactivation. However, we show here that cell chains ofE. coli tol-palmutants are connected by an incompletely processed peptidoglycan (PG) layer. Genetic suppressors of this defect were isolated and found to overproduce OM lipoproteins capable of cleaving the glycan strands of PG. Among the factors promoting cell separation in mutant cells was a protein of previously unknown function (YddW), which we have identified as a divisome-localized glycosyl hydrolase that cleaves peptide-free PG glycans. Overall, our results indicate that the cell chaining defect of Tol-Pal mutants cannot simply be interpreted as a defect in OM constriction. Rather, the complex also appears to be required for the activity of several OM-localized enzymes with cell wall remodeling activity. Thus, the Tol-Pal system may play a more general role in coordinating OM invagination with PG remodeling at the division site than previously appreciated.

Differentiation of the Bacterial Cell Division Site

1989 ◽  
pp. 1-31 ◽  
Author(s):  
William R. Cook ◽  
Piet A.J. de Boer ◽  
Lawrence I. Rothfield
Keyword(s):  
Cell Division ◽  
Bacterial Cell ◽  
Bacterial Cell Division ◽  
Division Site

scholarly journals Analytical ultracentrifugation and preliminary X-ray studies of the chloroplast envelope quinone oxidoreductase homologue fromArabidopsis thaliana

2015 ◽  
Vol 71 (4) ◽  
pp. 455-458 ◽  
Author(s):  
Sarah Mas y mas ◽  
Cécile Giustini ◽  
Jean-Luc Ferrer ◽  
Norbert Rolland ◽  
Gilles Curien ◽  
...  
Keyword(s):  
Analytical Ultracentrifugation ◽  
Alternative Pathway ◽  
Transit Peptide ◽  
Chloroplast Envelope ◽  
Quinone Oxidoreductase ◽  
Chloroplast Targeting ◽  
Data Set ◽  
Chloroplast Transit Peptide ◽  
Chloroplast Envelope Membrane ◽  
Living Organisms

Quinone oxidoreductases reduce a broad range of quinones and are widely distributed among living organisms. The chloroplast envelope quinone oxidoreductase homologue (ceQORH) fromArabidopsis thalianabinds NADPH, lacks a classical N-terminal and cleavable chloroplast transit peptide, and is transported through the chloroplast envelope membrane by an unknown alternative pathway without cleavage of its internal chloroplast targeting sequence. To unravel the fold of this targeting sequence and its substrate specificity, ceQORH fromA. thalianawas overexpressed inEscherichia coli, purified and crystallized. Crystals of apo ceQORH were obtained and a complete data set was collected at 2.34 Å resolution. The crystals belonged to space groupC2221, with two molecules in the asymmetric unit.

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

2006 ◽  
Vol 188 (5) ◽  
pp. 1680-1690 ◽  
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.

scholarly journals Chloroplast division checkpoint in eukaryotic algae

2016 ◽  
Vol 113 (47) ◽  
pp. E7629-E7638 ◽  
Author(s):  
Nobuko Sumiya ◽  
Takayuki Fujiwara ◽  
Atsuko Era ◽  
Shin-ya Miyagishima
Keyword(s):  
Cell Cycle ◽  
Host Cell ◽  
Cell Cycle Progression ◽  
Chloroplast Division ◽  
Dominant Negative ◽  
Cyanidioschyzon Merolae ◽  
Temperature Sensitive ◽  
Specific Expression ◽  
Cycle Progression ◽  
Division Site

Chloroplasts evolved from a cyanobacterial endosymbiont. It is believed that the synchronization of endosymbiotic and host cell division, as is commonly seen in existing algae, was a critical step in establishing the permanent organelle. Algal cells typically contain one or only a small number of chloroplasts that divide once per host cell cycle. This division is based partly on the S-phase–specific expression of nucleus-encoded proteins that constitute the chloroplast-division machinery. In this study, using the red alga Cyanidioschyzon merolae, we show that cell-cycle progression is arrested at the prophase when chloroplast division is blocked before the formation of the chloroplast-division machinery by the overexpression of Filamenting temperature-sensitive (Fts) Z2-1 (Fts72-1), but the cell cycle progresses when chloroplast division is blocked during division-site constriction by the overexpression of either FtsZ2-1 or a dominant-negative form of dynamin-related protein 5B (DRP5B). In the cells arrested in the prophase, the increase in the cyclin B level and the migration of cyclin-dependent kinase B (CDKB) were blocked. These results suggest that chloroplast division restricts host cell-cycle progression so that the cell cycle progresses to the metaphase only when chloroplast division has commenced. Thus, chloroplast division and host cell-cycle progression are synchronized by an interactive restriction that takes place between the nucleus and the chloroplast. In addition, we observed a similar pattern of cell-cycle arrest upon the blockage of chloroplast division in the glaucophyte alga Cyanophora paradoxa, raising the possibility that the chloroplast division checkpoint contributed to the establishment of the permanent organelle.

scholarly journals Assembly of bacterial cell division protein FtsZ into dynamic biomolecular condensates

2020 ◽  
Author(s):  
Miguel Ángel Robles-Ramos ◽  
Silvia Zorrilla ◽  
Carlos Alfonso ◽  
William Margolin ◽  
Germán Rivas ◽  
...  
Keyword(s):  
Cell Division ◽  
Bacterial Cell ◽  
Bound State ◽  
Bacterial Cell Division ◽  
Structural Element ◽  
Physiological Factors ◽  
General Role ◽  
E Coli ◽  
Division Site ◽  
Synthetic Cell

Biomolecular condensation through phase separation may be a novel mechanism to regulate bacterial processes, including cell division. Previous work revealed FtsZ, a protein essential for cytokinesis in most bacteria, and the E. coli division site selection factor SlmA form FtsZ∙SlmA biomolecular condensates. The absence of condensates composed solely of FtsZ under the conditions used in that study suggested this mechanism was restricted to nucleoid occlusion or SlmA-containing bacteria. Here we report that FtsZ alone can demix into condensates in bulk and when encapsulated in synthetic cell-like systems. Condensate assembly depends on FtsZ being in the GDP-bound state and on crowding conditions that promote its oligomerization. FtsZ condensates are dynamic and gradually convert into FtsZ filaments upon GTP addition. Notably, FtsZ lacking its C-terminal disordered region, a structural element likely to favor biomolecular condensation, also forms condensates, albeit less efficiently. The inherent tendency of FtsZ to form condensates susceptible to modulation by physiological factors, including binding partners, suggests that such mechanisms may play a more general role in bacterial cell division than initially envisioned.

scholarly journals Simulations suggest a constrictive force is required for Gram-negative bacterial cell division

2018 ◽  
Author(s):  
Lam T. Nguyen ◽  
Catherine M. Oikonomou ◽  
H. Jane Ding ◽  
Mohammed Kaplan ◽  
Qing Yao ◽  
...  
Keyword(s):  
Cell Wall ◽  
Simulation System ◽  
Mechanistic Models ◽  
Bacterial Cells ◽  
Bacterial Cell Division ◽  
Cell Wall Synthesis ◽  
Gram Negative ◽  
Division Site ◽  
Cell Wall Remodeling ◽  
Peptidoglycan Cell Wall

AbstractTo divide, Gram-negative bacterial cells must remodel their peptidoglycan cell wall to a smaller and smaller radius at the division site, but how this process occurs remains debated. While the tubulin homolog FtsZ is thought to generate a constrictive force, it has also been proposed that cell wall remodeling alone is sufficient to drive membrane constriction, possibly via a make-before-break mechanism in which new hoops of cell wall are made inside the existing hoops (make) before bonds in the existing wall are cleaved (break). Previously, we constructed software, REMODELER 1, to simulate cell wall remodeling in rod-shaped bacteria during growth. Here, we used this software as the basis for an expanded simulation system, REMODELER 2, which we used to explore different mechanistic models of cell wall division. We found that simply organizing the cell wall synthesis complexes at the midcell was not sufficient to cause wall invagination, even with the implementation of a make-before-break mechanism. Applying a constrictive force at the midcell could drive division if the force was sufficiently large to initially constrict the midcell into a compressed state before new hoops of relaxed cell wall were incorporated between existing hoops. Adding a make-before-break mechanism could drive division with a smaller constrictive force sufficient to bring the midcell peptidoglycan into a relaxed, but not necessarily compressed, state.

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