scholarly journals Cell-free biogenesis of bacterial division proto-rings that can constrict liposomes

2020 ◽  
Author(s):  
Elisa Godino ◽  
Jonás Noguera López ◽  
Ilias Zarguit ◽  
Anne Doerr ◽  
Mercedes Jimenez ◽  
...  
Keyword(s):  
Cytoskeletal Proteins ◽  
Division Site ◽  
Artificial Cell ◽  
Bacterial Division ◽  
Synthetic Cell ◽  
Free Gene ◽  
Bacterial Cell Cycle ◽  
Cytoskeletal Elements ◽  
Planar Membranes ◽  
Genetic Programme

ABSTRACTA major challenge towards the realization of an autonomous synthetic cell resides in the encoding of a division machinery in a genetic programme. A key event in the bacterial cell cycle is the assembly of cytoskeletal proteins into a ring that defines the division site. At the onset of the formation of the Escherichia coli divisome, a proto-ring consisting of FtsZ and its membrane recruiting proteins takes place. Here, we show that FtsA-FtsZ ring-like structures driven by cell-free gene expression can be reconstituted on planar membranes and inside liposome compartments. Such cytoskeletal structures are found to constrict the membrane and generate budding vesicles, a phenotype that has not been reported before. Additional expression of the FtsZ cross-linker protein ZapA yields more rigid FtsZ bundles that attach to the membrane but fail to produce budding spots or necks in liposomes. These results provide new insights on the self-organization of basic cytoskeletal elements involved in bacterial division. Moreover, they demonstrate that gene-directed protein synthesis and assembly of membrane-constricting FtsZ-rings can be combined in a liposome-based artificial cell.

scholarly journals Cell-free biogenesis of bacterial division proto-rings that can constrict liposomes

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Elisa Godino ◽  
Jonás Noguera López ◽  
Ilias Zarguit ◽  
Anne Doerr ◽  
Mercedes Jimenez ◽  
...  
Keyword(s):  
Cytoskeletal Proteins ◽  
Ftsz Ring ◽  
Division Site ◽  
Artificial Cell ◽  
Bacterial Division ◽  
Synthetic Cell ◽  
Free Gene ◽  
Bacterial Cell Cycle ◽  
Planar Membranes ◽  
Genetic Programme

AbstractA major challenge towards the realization of an autonomous synthetic cell resides in the encoding of a division machinery in a genetic programme. In the bacterial cell cycle, the assembly of cytoskeletal proteins into a ring defines the division site. At the onset of the formation of the Escherichia coli divisome, a proto-ring consisting of FtsZ and its membrane-recruiting proteins takes place. Here, we show that FtsA-FtsZ ring-like structures driven by cell-free gene expression can be reconstituted on planar membranes and inside liposome compartments. Such cytoskeletal structures are found to constrict the liposome, generating elongated membrane necks and budding vesicles. Additional expression of the FtsZ cross-linker protein ZapA yields more rigid FtsZ bundles that attach to the membrane but fail to produce budding spots or necks in liposomes. These results demonstrate that gene-directed protein synthesis and assembly of membrane-constricting FtsZ-rings can be combined in a liposome-based artificial cell.

scholarly journals Specific release of membrane-bound annexin II and cortical cytoskeletal elements by sequestration of membrane cholesterol.

1997 ◽  
Vol 8 (3) ◽  
pp. 533-545 ◽  
Author(s):  
T Harder ◽  
R Kellner ◽  
R G Parton ◽  
J Gruenberg
Keyword(s):  
Actin Cytoskeleton ◽  
Cytoskeletal Proteins ◽  
Annexin Ii ◽  
Dependent Manner ◽  
Cortical Actin ◽  
Independent Manner ◽  
Low Concentrations ◽  
Early Endosomes ◽  
Associated Proteins ◽  
Cytoskeletal Elements

Annexin II is an abundant protein which is present in the cytosol and on the cytoplasmic face of plasma membrane and early endosomes. It is generally believed that this association occurs via Ca(2+)-dependent binding to lipids, a mechanism typical for the annexin protein family. Although previous studies have shown that annexin II is involved in early endosome dynamics and organization, the precise biological role of the protein is unknown. In this study, we found that approximately 50% of the total cellular annexin was associated with membranes in a Ca(2+)-independent manner. This binding was extremely tight, since it resisted high salt and, to some extent, high pH treatments. We found, however, that membrane-associated annexin II could be quantitatively released by low concentrations of the cholesterol-sequestering agents filipin and digitonin. Both treatments released an identical and limited set of proteins but had no effects on other membrane-associated proteins. Among the released proteins, we identified, in addition to annexin II itself, the cortical cytoskeletal proteins alpha-actinin, ezrin and moesin, and membrane-associated actin. Our biochemical and immunological observations indicate that these proteins are part of a complex containing annexin II and that stability of the complex is sensitive to cholesterol sequestering agents. Since annexin II is tightly membrane-associated in a cholesterol-dependent manner, and since it seems to interact physically with elements of the cortical actin cytoskeleton, we propose that the protein serves as interface between membranes containing high amounts of cholesterol and the actin cytoskeleton.

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.

Intracellular Cytoskeletal Elements and Cytoskeletons in Bacteria

2007 ◽  
Vol 90 (2-3) ◽  
pp. 73-102 ◽  
Author(s):  
Mohamed H.F. Madkour ◽  
Frank Mayer
Keyword(s):  
Shape Control ◽  
Control Cell ◽  
Elongation Factor ◽  
Cytoskeletal Proteins ◽  
New Drugs ◽  
Cell Functions ◽  
Short Period ◽  
New Thinking ◽  
Control Cell Division ◽  
Cytoskeletal Elements

Within a short period of time after the discovery of bacterial cytoskletons, major progress had been made in areas such as general spatial layout of cytoskeletons, their involvement in a variety of cell functions (shape control, cell division, chromosome segregation, cell motility). This progress was achieved by application of advanced investigation techniques. Homologs of eukaryotic actin, tubulin, and intermediate filaments were found in bacteria; cytoskeletal proteins not closely or not at all related to any of these major cytoskeletal proteins were discovered in a number of bacteria such as Mycoplasmas, Spiroplasmas, Spirochetes, Treponema, Caulobacter. A structural role for bacterial elongation factor Tu was indicated. On the basis of this new thinking, new approaches in biotechnology and new drugs are on the way.

Synthetic organelles

2019 ◽  
Vol 3 (5) ◽  
pp. 587-595 ◽  
Author(s):  
Friedrich C. Simmel
Keyword(s):  
Short Review ◽  
Review Article ◽  
Chemical Processes ◽  
Enzyme Reactions ◽  
Chemical Gradients ◽  
Cell Structures ◽  
Synthetic Cell ◽  
Recent Developments ◽  
Free Gene ◽  
Specific Synthesis

One approach towards the creation of bottom-up synthetic biological systems of higher complexity relies on the subcompartmentalization of synthetic cell structures using artificially generated organelles — roughly mimicking the architecture of eukaryotic cells. Organelles create dedicated chemical environments for specific synthesis tasks — they separate incompatible processes from each other and help to create or maintain chemical gradients that drive other chemical processes. Artificial organelles have been used to compartmentalize enzyme reactions, to generate chemical fuels via photosynthesis and oxidative phosphorylation, and they have been utilized to spatially organize cell-free gene expression reactions. In this short review article, we provide an overview of recent developments in this field, which involve a wide variety of compartmentalization strategies ranging from lipid and polymer membrane systems to membraneless compartmentalization via coacervation.

Cytosolic phox proteins interact with and regulate the assembly of coronin in neutrophils

1997 ◽  
Vol 110 (24) ◽  
pp. 3071-3081 ◽  
Author(s):  
A. Grogan ◽  
E. Reeves ◽  
N. Keep ◽  
F. Wientjes ◽  
N.F. Totty ◽  
...  
Keyword(s):  
Binding Protein ◽  
Cytoskeletal Proteins ◽  
Actin Binding ◽  
Similar Distribution ◽  
Binding Studies ◽  
Spatial Organisation ◽  
Binding Partner ◽  
Specific Proteins ◽  
Temporal And Spatial ◽  
Cytoskeletal Elements

The NADPH oxidase generates microbicidal superoxide in phagocytes, and when defective it leads to chronic granulomatous disease (CGD). Oxidase specific proteins in the cytosol, p47phox and p67phox, as well as the small GTP binding protein p21rac are important for activation of superoxide production. Because the activity of this oxidase is normally tightly restricted to the phagocytic vacuole, and its temporal and spatial organisation might be regulated by cytoskeletal proteins, we examined the cytosolic phox proteins for interactions with cytoskeletal elements. p67phox copurified with a 57 kDa protein, identified as coronin, an actin binding protein that is important for movement and phagocytosis in Dictyostelium. Binding studies revealed that coronin attaches to the C-terminal half of p40phox, a binding partner of p67phox. The phox proteins and coronin had a similar distribution in the cell, and both accumulated around the phagocytic vacuole. PMA activation of adherent neutrophils resulted in a major rearrangement of these proteins, and of actin, which were lost from the periphery of the cell and condensed around the nucleus. The rearrangement of F-actin and coronin in adherent cells, were absent, or markedly diminished, in cells from patients lacking p47phox or p67phox in which an abnormally large proportion of the coronin was present as part of a large complex. The cytosolic phox proteins might play a regulatory role in the reorganisation of the cytoskeleton accompanying superoxide generation.

scholarly journals Preparation and properties of a complex from rat liver of polyribosomes with components of the cytoskeleton

1983 ◽  
Vol 216 (1) ◽  
pp. 215-226 ◽  
Author(s):  
A Adams ◽  
E G Fey ◽  
S F Pike ◽  
C J Taylorson ◽  
H A White ◽  
...  
Keyword(s):  
Rat Liver ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Gel Filtration ◽  
Subcellular Fractionation ◽  
Cytoskeletal Proteins ◽  
Deoxyribonuclease I ◽  
Microsomal Membranes ◽  
Cytoskeletal Elements ◽  
Triton X

Gel filtration with 1% agarose (Bio-Gel A-150m) separates polyribosomes bound to microsomal membranes from ‘free’ polyribosomes when these fractions are prepared by standard centrifugal techniques. However, when polyribosomes contained in an unfractionated postmitochondrial supernatant are run on an identical column, over 90% of the total polyribosomes are present as aggregates, designated ‘membrane-cytomatrix’, which are eluted in the column void volume. Polyribosomes are not released from these aggregates on removal of microsomal phospholipids by treatment of postmitochondrial supernatant with 1% Triton X-100, a neutral detergent. The aggregates are disrupted by the usual ultracentrifugation techniques used in subcellular fractionation. After treatment of membrane-cytomatrix with Triton X-100 to remove phospholipids and membrane proteins, 58% of the polyribosomes still remain associated with protein-containing complexes in the form of a cytomatrix and are not ‘free’. Preparations of both membrane-cytomatrix and cytomatrix are capable of sustained protein synthesis. Sodium dodecyl sulphate/polyacrylamide-gel electrophoresis revealed that the cytoskeletal proteins actin and myosin are present in the cytomatrix. Incubation of cytomatrix preparations with the actin-depolymerizing agent deoxyribonuclease I caused release of the polyribosomes. Polyribosome release by deoxyribonuclease I was prevented by prior incubation with phalloidin, which is known to stabilize F-actin. Thus polyribosomes are associated with cytoskeletal elements in rat liver, and this association is dependent on polymeric forms of actin.

scholarly journals Clathrin is axonally transported as part of slow component b: the microfilament complex.

1981 ◽  
Vol 88 (1) ◽  
pp. 172-178 ◽  
Author(s):  
J A Garner ◽  
R J Lasek
Keyword(s):  
Guinea Pig ◽  
Slow Component ◽  
Polyacrylamide Gel Electrophoresis ◽  
Cytoskeletal Proteins ◽  
Neurofilament Protein ◽  
Associated Proteins ◽  
Tritiated Amino Acids ◽  
Cytoskeletal Elements ◽  
Guinea Pig Brain

During axonal transport, membranes travel down axons at a rapid rate, whereas the cytoskeletal elements travel in either of two slow components, SCa (with tubulin and neurofilament protein) and SCb (with actin). Clathrin, the highly ordered, structural coat protein of coated vesicles, has recently been shown to be able to interact in vitro with cytoskeletal proteins in addition to membranes. The present study examines whether clathrin travels preferentially with the membrane elements or the cytoskeletal elements when it is axonally transported. Guinea pig visual system was labeled with tritiated amino acids. Radioactive SDS-polyacrylamide gel electrophoresis profiles from the major components of transport were coelectrophoresed with clathrin. Only SCb had a band comigrating with clathrin. In addition, radioactive clathrin was purified from guinea pig brain containing only radioactive SCb polypeptides. Kinetic analysis of the putative clathrin band in SCb revealed that it travels entirely within the SCb wave. Thus we conclude that clathrin travels preferentially with the cytoskeletal proteins making up SCb, rather than with the membranes and membrane-associated proteins in the fast component.

scholarly journals Cytoskeleton of Apicomplexan Parasites

2002 ◽  
Vol 66 (1) ◽  
pp. 21-38 ◽  
Author(s):  
Naomi S. Morrissette ◽  
L. David Sibley
Keyword(s):  
Cytoskeletal Proteins ◽  
Opportunistic Pathogens ◽  
Protozoan Parasites ◽  
Apicomplexan Parasites ◽  
Obligate Intracellular ◽  
Intracellular Parasites ◽  
Eimeria Spp ◽  
Cytoskeletal Elements ◽  
Theileria Spp

SUMMARY The Apicomplexa are a phylum of diverse obligate intracellular parasites including Plasmodium spp., the cause of malaria; Toxoplasma gondii and Cryptosporidium parvum, opportunistic pathogens of immunocompromised individuals; and Eimeria spp. and Theileria spp., parasites of considerable agricultural importance. These protozoan parasites share distinctive morphological features, cytoskeletal organization, and modes of replication, motility, and invasion. This review summarizes our current understanding of the cytoskeletal elements, the properties of cytoskeletal proteins, and the role of the cytoskeleton in polarity, motility, invasion, and replication. We discuss the unusual properties of actin and myosin in the Apicomplexa, the highly stereotyped microtubule populations in apicomplexans, and a network of recently discovered novel intermediate filament-like elements in these parasites.

scholarly journals Basic proteins of the perinuclear theca of mammalian spermatozoa and spermatids: a novel class of cytoskeletal elements.

1987 ◽  
Vol 105 (3) ◽  
pp. 1105-1120 ◽  
Author(s):  
F J Longo ◽  
G Krohne ◽  
W W Franke
Keyword(s):  
Plasma Membrane ◽  
Complex Structure ◽  
Sperm Head ◽  
Cytoskeletal Proteins ◽  
Electron Microscopic Level ◽  
Intermediate Filament Proteins ◽  
Basic Proteins ◽  
Nuclear Lamins ◽  
Perinuclear Theca ◽  
Cytoskeletal Elements

The nuclei of bovine spermatids and spermatozoa are surrounded by dense cytoplasmic webs sandwiched between the nuclear envelope and the acrosome and plasma membrane, respectively, filling most of the cytoplasmic space of the sperm head. This web contains a complex structure, the perinuclear theca, which is characterized by resistance to extractions in nondenaturing detergents and high salt buffers, and can be divided into two major subcomponents, the subacrosomal layer and the postacrosomal calyx. Using calyces isolated from bull and rat spermatozoa we have identified two kinds of basic proteins as major constituents of the thecal structure and have localized them by specific antibodies at the light and electron microscopic level. These are an Mr 60,000 protein, termed calicin, localized almost exclusively to the calyx, and a group of multiple-band polypeptides (MBP; Mr 56,000-74,000), which occur in both the calyx and the subacrosomal layer. The polypeptides of the MBP group are immunologically related to each other, but unrelated, by antibody reactions and peptide maps, to calicin. We show that these basic cytoskeletal proteins are first detectable in the round spermatid stage. As we have not detected any intermediate filament proteins and proteins related to nuclear lamins of somatic cells in sperm heads, we conclude that the perinuclear theca and its constituents, calicin and MBP proteins, are the predominant cytoskeletal elements of the sperm head. Immunologically cross-reacting polypeptides with similar properties have been identified in the heads of rat and human spermatozoa. We speculate that these insoluble basic proteins contribute, during spermiogenesis, to the formation of the perinuclear theca as an architectural element involved in the shape changes and the intimate association of the nucleus with the acrosome and the plasma membrane.

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