The Origin of the Eukaryotic Cell Based on Conservation of Existing Interfaces

2006 ◽  
Vol 12 (4) ◽  
pp. 513-523 ◽  
Author(s):  
Albert D. G. de Roos
Keyword(s):  
Plasma Membrane ◽  
Protein Interactions ◽  
Self Assembly ◽  
Evolutionary Model ◽  
Lipid Vesicles ◽  
Eukaryotic Cell ◽  
The Self ◽  
Lipid Protein Interactions

Current theories about the origin of the eukaryotic cell all assume that during evolution a prokaryotic cell acquired a nucleus. Here, it is shown that a scenario in which the nucleus acquired a plasma membrane is inherently less complex because existing interfaces remain intact during evolution. Using this scenario, the evolution to the first eukaryotic cell can be modeled in three steps, based on the self-assembly of cellular membranes by lipid-protein interactions. First, the inclusion of chromosomes in a nuclear membrane is mediated by interactions between laminar proteins and lipid vesicles. Second, the formation of a primitive endoplasmic reticulum, or exomembrane, is induced by the expression of intrinsic membrane proteins. Third, a plasma membrane is formed by fusion of exomembrane vesicles on the cytoskeletal protein scaffold. All three self-assembly processes occur both in vivo and in vitro. This new model provides a gradual Darwinistic evolutionary model of the origins of the eukaryotic cell and suggests an inherent ability of an ancestral, primitive genome to induce its own inclusion in a membrane.

scholarly journals A natural product inhibits the initiation of α-synuclein aggregation and suppresses its toxicity

2017 ◽  
Vol 114 (6) ◽  
pp. E1009-E1017 ◽  
Author(s):  
Michele Perni ◽  
Céline Galvagnion ◽  
Alexander Maltsev ◽  
Georg Meisl ◽  
Martin B. D. Müller ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Natural Product ◽  
Self Assembly ◽  
Lipid Membranes ◽  
Neuroblastoma Cells ◽  
Lipid Vesicles ◽  
Human Neuroblastoma

The self-assembly of α-synuclein is closely associated with Parkinson’s disease and related syndromes. We show that squalamine, a natural product with known anticancer and antiviral activity, dramatically affects α-synuclein aggregation in vitro and in vivo. We elucidate the mechanism of action of squalamine by investigating its interaction with lipid vesicles, which are known to stimulate nucleation, and find that this compound displaces α-synuclein from the surfaces of such vesicles, thereby blocking the first steps in its aggregation process. We also show that squalamine almost completely suppresses the toxicity of α-synuclein oligomers in human neuroblastoma cells by inhibiting their interactions with lipid membranes. We further examine the effects of squalamine in a Caenorhabditis elegans strain overexpressing α-synuclein, observing a dramatic reduction of α-synuclein aggregation and an almost complete elimination of muscle paralysis. These findings suggest that squalamine could be a means of therapeutic intervention in Parkinson’s disease and related conditions.

scholarly journals Human Organ-Specific 3D Cancer Models Produced by the Stromal Self-Assembly Method of Tissue Engineering for the Study of Solid Tumors

2020 ◽  
Vol 2020 ◽  
pp. 1-23 ◽  
Author(s):  
Vincent Roy ◽  
Brice Magne ◽  
Maude Vaillancourt-Audet ◽  
Mathieu Blais ◽  
Stéphane Chabaud ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Tumor Microenvironment ◽  
Self Assembly ◽  
The Self ◽  
Human Organ ◽  
Assembly Method ◽  
Cancer Models ◽  
Organ Specific

Cancer research has considerably progressed with the improvement of in vitro study models, helping to understand the key role of the tumor microenvironment in cancer development and progression. Over the last few years, complex 3D human cell culture systems have gained much popularity over in vivo models, as they accurately mimic the tumor microenvironment and allow high-throughput drug screening. Of particular interest, in vitrohuman 3D tissue constructs, produced by the self-assembly method of tissue engineering, have been successfully used to model the tumor microenvironment and now represent a very promising approach to further develop diverse cancer models. In this review, we describe the importance of the tumor microenvironment and present the existing in vitro cancer models generated through the self-assembly method of tissue engineering. Lastly, we highlight the relevance of this approach to mimic various and complex tumors, including basal cell carcinoma, cutaneous neurofibroma, skin melanoma, bladder cancer, and uveal melanoma.

Non-Covalent Polyvalent Ligands by Self-Assembly of Small Glycodendrimers: A Novel Concept for the Inhibition of Polyvalent Carbohydrate-Protein Interactions In Vitro and In Vivo

2006 ◽  
Vol 12 (1) ◽  
pp. 99-117 ◽  
Author(s):  
Gebhard Thoma ◽  
Markus B. Streiff ◽  
Andreas G. Katopodis ◽  
Rudolf O. Duthaler ◽  
Nicolas H. Voelcker ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Self Assembly ◽  
Polyvalent Ligands ◽  
Novel Concept

scholarly journals Yeast proteins associated with microtubules in vitro and in vivo.

1992 ◽  
Vol 3 (1) ◽  
pp. 29-47 ◽  
Author(s):  
G Barnes ◽  
K A Louie ◽  
D Botstein
Keyword(s):  
Self Assembly ◽  
Synthetic Peptides ◽  
Immunofluorescence Microscopy ◽  
The Self ◽  
Microtubule Associated Proteins ◽  
Amino Terminal ◽  
Novel Proteins ◽  
Associated Proteins

Conditions were established for the self-assembly of milligram amounts of purified Saccharomyces cerevisiae tubulin. Microtubules assembled with pure yeast tubulin were not stabilized by taxol; hybrid microtubules containing substoichiometric amounts of bovine tubulin were stabilized. Yeast microtubule-associated proteins (MAPs) were identified on affinity matrices made from hybrid and all-bovine microtubules. About 25 yeast MAPs were isolated. The amino-terminal sequences of several of these were determined: three were known metabolic enzymes, two were GTP-binding proteins (including the product of the SAR1 gene), and three were novel proteins not found in sequence databases. Affinity-purified antisera were generated against synthetic peptides corresponding to two of the apparently novel proteins (38 and 50 kDa). Immunofluorescence microscopy showed that both these proteins colocalize with intra- and extranuclear microtubules in vivo.

Acidity-responsive shell-sheddable camptothecin-based nanofibers for carrier-free cancer drug delivery

Nanoscale ◽  
2019 ◽  
Vol 11 (34) ◽  
pp. 15907-15916 ◽  
Author(s):  
Zhuha Zhou ◽  
Ying Piao ◽  
Lingqiao Hao ◽  
Guanyu Wang ◽  
Zhuxian Zhou ◽  
...  
Keyword(s):  
Self Assembly ◽  
Surface Coating ◽  
Tumor Tissue ◽  
The Self ◽  
Cancer Drug ◽  
Ph Responsive ◽  
Carrier Free ◽  
Cancer Drug Delivery

pH-responsive nanofibers are obtained by the self-assembly of the camptothecin prodrug and surface-coating, which can efficiently enter cancer cells in vitro and penetrate deep into tumor tissue in vivo.

scholarly journals Phase Separation of Shell Protein and Enzyme: An Insight into the Biogenesis of a Prokaryotic Metabolosome

2022 ◽  
Author(s):  
Gaurav Kumar ◽  
Sharmistha Sinha
Keyword(s):  
Phase Separation ◽  
Protein Interactions ◽  
Self Assembly ◽  
Bacterial Species ◽  
Protein Structures ◽  
The Self ◽  
Liquid Droplets ◽  
Shell Protein ◽  
Shell Proteins

Bacterial microcompartments are substrate specific metabolic modules that are conditionally expressed in certain bacterial species. These all protein structures have size in the range of 100-150 nm and are formed by the self-assembly of thousands of protein subunits, all encoded by genes belonging to a single operon. The operon contains genes that encode for both enzymes and shell proteins. The shell proteins self-assemble to form the outer coat of the compartment and enzymes are encapsulated within. A perplexing question in MCP biology is to understand the mechanism which governs the formation of these small yet complex assemblages of proteins. In this work we use 1,2-propanediol utilization microcompartments (PduMCP) as a paradigm to identify the factors that drive the self-assembly of MCP proteins. We find that a major shell protein PduBB tend to self-assemble under macromolecular crowded environment and suitable ionic strength. Microscopic visualization and biophysical studies reveal phase separation to be the principle mechanism behind the self-association of shell protein in the presence of salts and macromolecular crowding. The shell protein PduBB interacts with the enzyme diol-dehydratase PduCDE and co-assemble into phase separated liquid droplets. The co-assembly of PduCDE and PduBB results in the enhancement of catalytic activity of the enzyme. A combination of spectroscopic and biochemical techniques shows the relevance of divalent cation Mg2+ in providing stability to intact PduMCP in vivo. Together our results suggest a combination of protein-protein interactions and phase separation guiding the self-assembly of Pdu shell protein and enzyme in solution phase.

scholarly journals DNA-Encircled Lipid Bilayers

2018 ◽  
Author(s):  
Katarina Iric ◽  
Madhumalar Subramanian ◽  
Jana Oertel ◽  
Nayan P. Agarwal ◽  
Michael Matthies ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Lipid Bilayer ◽  
Lipid Bilayers ◽  
Protein Interactions ◽  
Protein Function ◽  
Dna Nanotechnology ◽  
Lipid Vesicles ◽  
Associated Proteins

ABSTRACTLipid bilayers and lipid-associated proteins play a crucial role in biology. As in vivo studies and manipulation are inherently difficult, several membrane-mimetic systems have been developed to enable investigation of lipidic phases, lipid-protein interactions, membrane protein function and membrane structure in vitro. Controlling the size and shape, or site-specific functionalization is, however, difficult to achieve with established membrane mimetics based on membrane scaffolding proteins, polymers or peptides. In this work, we describe a route to leverage the unique programmability of DNA nanotechnology and create DNA-encircled bilayers (DEBs), which are made of multiple copies of an alkylated oligonucleotide hybridized to a single-stranded minicircle. To stabilize the hydrophobic rim of the lipid bilayer, and to prevent formation of lipid vesicles, we introduced up to 2 alkyl chains per helical that point to the inside of the toroidal DNA ring and interact with the hydrophobic side chains of the encapsulated lipid bilayer. The DEB approach described herein provides unprecedented control of size, and allows the orthogonal functionalizations and arrangement of engineered membrane nanoparticles and will become a valuable tool for biophysical investigation of lipid phases and lipid-associated proteins and complexes including structure determination of membrane proteins and pharmacological screenings of membrane proteins.

Mechanism of the regulation of type IB phosphoinositide 3OH-kinase byG-protein βγ subunits

2002 ◽  
Vol 362 (3) ◽  
pp. 725-731 ◽  
Author(s):  
Sonja KRUGMANN ◽  
Matthew A. COOPER ◽  
Dudley H. WILLIAMS ◽  
Phillip T. HAWKINS ◽  
Len R. STEPHENS
Keyword(s):  
Plasma Membrane ◽  
Surface Plasmon Resonance ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Lipid Vesicles ◽  
Dissociation Rate ◽  
Lipid Monolayers ◽  
Dissociation Rate Constants

Type IB phosphoinositide 3OH-kinase (PI3K) is activated by G-protein βγ subunits (Gβγs). The enzyme is soluble and largely cytosolic in vivo. Its substrate, PtdIns(4,5)P2, and the Gβγs are localized at the plasma membrane. We have addressed the mechanism by which Gβγs regulate the PI3K using an in vitro approach. We used sedimentation assays and surface plasmon resonance to determine association of type IB PI3K with lipid monolayers and vesicles of varying compositions, some of which had Gβγs incorporated. Association and dissociation rate constants were determined. Our results indicated that in an assay situation in vitro the majority of PI3K will be associated with lipid vesicles, irrespective of the presence or absence of Gβγs. In line with this, a constitutively active membrane-targeted PI3K construct could still be activated substantially by Gβγs in vitro. We conclude that Gβγs activate type IB PI3K by a mechanism other than translocation to the plasma membrane.

scholarly journals Synergistic inhibition of metastatic breast cancer by dual-chemotherapy with excipient-free rhein/DOX nanodispersions

2020 ◽  
Author(s):  
Ruoning Wang ◽  
Yujie Yang ◽  
Mengmeng Yang ◽  
Dandan Yuan ◽  
Jinyu Huang ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Metastatic Breast Cancer ◽  
Self Assembly ◽  
Metastatic Cancer ◽  
Metastatic Breast ◽  
Md Simulations ◽  
Intermolecular Forces ◽  
The Self

Abstract Background: The treatment of metastatic cancer continues to be very challenging worldwide. Notably, excipient-free nanodispersions that are entirely composed of pharmaceutically active molecules are regarded as promising candidates for the next generation of drug formulations. These molecules are mainly formulated from the self-assembly of drug molecules that enable the safe and effective delivery of therapeutic drugs to local diseased lesions. Herein, we developed a novel and green approach for preparing nanoparticles via the self-assembly of rhein (RHE) and doxorubicin (DOX) molecules, named RHE/DOX nanoparticles (RD NPs); this assembly was associated with π−π stacking interactions and did not involve any organic solvents. Results：Molecular dynamics (MD) simulations showed that DOX molecules tend to assemble around RHE molecules through intermolecular forces. With the advantage of nanosizing, RD NPs improved the intracellular drug retention of DOX. As a dual-drug-loaded nanoformulation, the toxicity of RD NPs to tumor cells in vitro was synergistically enhanced. The combination of DOX and RHE in nanoparticles exhibited a synergistic effect with a combination index (CI) value of 0.51 and showed a stronger ability to induce cell apoptosis compared to that of free DOX. Furthermore, RD NPs treatment not only effectively suppressed primary tumor growth but also successfully inhibited tumor metastasis both in vitro and in vivo, with a good safety profile. Conclusion: The generation of pure nanodrugs via a self-assembly approach might be an option and may provide inspiration for the fabrication of new excipient-free nanodispersions, especially for two small molecular antitumor drugs that could potentially have synergistic antiproliferation effects against metastatic breast cancer.

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