scholarly journals Membranes, energetics, and evolution across the prokaryote-eukaryote divide

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Michael Lynch ◽  
Georgi K Marinov
Keyword(s):  
Evolutionary History ◽  
Atp Synthesis ◽  
Eukaryotic Cell ◽  
Eukaryotic Cells ◽  
Evolutionary Transition ◽  
Intracellular Membrane ◽  
Mitochondrial Membranes ◽  
Membrane Bound ◽  
Organismal Complexity ◽  
Lines Of Evidence

The evolution of the eukaryotic cell marked a profound moment in Earth’s history, with most of the visible biota coming to rely on intracellular membrane-bound organelles. It has been suggested that this evolutionary transition was critically dependent on the movement of ATP synthesis from the cell surface to mitochondrial membranes and the resultant boost to the energetic capacity of eukaryotic cells. However, contrary to this hypothesis, numerous lines of evidence suggest that eukaryotes are no more bioenergetically efficient than prokaryotes. Thus, although the origin of the mitochondrion was a key event in evolutionary history, there is no reason to think membrane bioenergetics played a direct, causal role in the transition from prokaryotes to eukaryotes and the subsequent explosive diversification of cellular and organismal complexity.

Mitochondria Are Fundamental for the Emergence of Metazoans: On Metabolism, Genomic Regulation, and the Birth of Complex Organisms

2020 ◽  
Vol 54 (1) ◽  
pp. 151-166 ◽  
Author(s):  
Hadar Medini ◽  
Tal Cohen ◽  
Dan Mishmar
Keyword(s):  
Gene Expression ◽  
Chromatin Remodeling ◽  
Genetic System ◽  
Eukaryotic Cell ◽  
Eukaryotic Cells ◽  
Intracellular Bacteria ◽  
Human Disorders ◽  
Genomic Regulation ◽  
Lines Of Evidence

Out of many intracellular bacteria, only the mitochondria and chloroplasts abandoned their independence billions of years ago and became endosymbionts within the host eukaryotic cell. Consequently, one cannot grow eukaryotic cells without their mitochondria, and the mitochondria cannot divide outside of the cell, thus reflecting interdependence. Here, we argue that such interdependence underlies the fundamental role of mitochondrial activities in the emergence of metazoans. Several lines of evidence support our hypothesis: ( a) Differentiation and embryogenesis rely on mitochondrial function; ( b) mitochondrial metabolites are primary precursors for epigenetic modifications (such as methyl and acetyl), which are critical for chromatin remodeling and gene expression, particularly during differentiation and embryogenesis; and ( c) mitonuclear coregulation adapted to accommodate both housekeeping and tissue-dependent metabolic needs. We discuss the evolution of the unique mitochondrial genetic system, mitochondrial metabolites, mitonuclear coregulation, and their critical roles in the emergence of metazoans and in human disorders.

scholarly journals Prototypic SNARE proteins are encoded in the genomes of Heimdallarchaeota, potentially bridging the gap between the prokaryotes and eukaryotes

2019 ◽  
Author(s):  
Emilie Neveu ◽  
Dany Khalifeh ◽  
Nicolas Salamin ◽  
Dirk Fasshauer
Keyword(s):  
Gene Transfer ◽  
Eukaryotic Cell ◽  
Snare Proteins ◽  
Eukaryotic Cells ◽  
Endomembrane System ◽  
Intracellular Space ◽  
Sensitive Factor ◽  
Genes Encoding ◽  
Membrane Bound ◽  
Material Exchange

AbstractA defining feature of eukaryotic cells is the presence of numerous membrane-bound organelles that subdivide the intracellular space into distinct compartments. How the eukaryotic cell acquired its internal complexity is still poorly understood. Material exchange among most organelles occurs via vesicles that bud off from a source and specifically fuse with a target compartment. Central players in the vesicle fusion process are the Soluble N-ethylmaleimide-sensitive factor Attachment protein REceptor (SNARE) proteins. These small tail-anchored (TA) membrane proteins zipper into elongated four-helix bundles that pull membranes together1–3. SNARE proteins are highly conserved among eukaryotes but are thought to be absent in prokaryotes. Here, we identified SNARE-like factors in the genomes of uncultured organisms of Asgard archaea of the Heimdallarchaeota clade4,5, which are thought to be the closest living relatives of eukaryotes. Biochemical experiments show that the archaeal SNARE-like proteins can interact with eukaryotic SNARE proteins. We did not detect SNAREs in α-proteobacteria, the closest relatives of mitochondria, but identified several genes encoding for SNARE proteins in γ-proteobacteria of the order Legionellales, pathogens that live inside eukaryotic cells. Very probably, their SNAREs stem from lateral gene transfer from eukaryotes. Together, this suggests that the diverse set of eukaryotic SNAREs evolved from an archaeal precursor. However, whether Heimdallarchaeota actually have a simplified endomembrane system will only be seen when we succeed studying these organisms under the microscope.

Some Aspects of the Polyhexamethyleneguanidine Salts Effect on Cell Cultures

2014 ◽  
Vol 1 (1) ◽  
pp. 62-67 ◽  
Author(s):  
M. Mandygra ◽  
A. Lysytsia
Keyword(s):  
Proliferative Activity ◽  
Cell Monolayer ◽  
Eukaryotic Cell ◽  
Culture Methods ◽  
Cellular Processes ◽  
Negative Effect ◽  
Membrane Bound ◽  
Membrane Bound Enzymes ◽  
Anion Type ◽  
Cell Culture Methods

Aim. To investigate the effect of polyhexamethyleneguanidine (PHMG) to eukaryotic cell culture. Methods. The passaged bovine tracheal cells culture (TCC) and primary culture of chicken embryo fi broblasts (FCE) were used in the experiments. TCC and FCE monolayers were treated with aqueous solutions of PHMG chloride or succinate. The method of PHMG polycation adsorption to the cells’ plasma membrane together with microscopy were applied. Results. The dependence of PHMG effect on the eukaryotic cells on the agent concentration, duration of exposure and the anion type has been fi xed. The PHMG concentration of 10 –5 per cent (0.1 μg/ml) never causes degradation of the previously formed cell monolayer, while the higher concentrations damage it. The conditions of the PHMG chloride and succinate’s negative effect on cell proliferation and inhibition of monolayer formation were determined. The hypothesis that under certain conditions PHMG stimulates the proliferative activity of the cells has been confi rmed. Stimulation may be associated with non-specifi c stress adaptation of cells. In this case, it is due to modifi cations of the cell membrane after PHMG adsorption to it. Conclusions. PHMG polycation binds with the membrane’s phosphoglycerides fi rmly and irreversibly. A portion of the lipids are removed from participation in the normal cellular processes at that. At the same time, the synthesis of new lipids and membrane-bound enzymes is probably accelerated. The phospholip ids’ neogenesis acceleration can stimulate mitosis under certain conditions. The obtained results can be used in the biotechnologies.

scholarly journals Origin of the Eukaryotic Cell

2017 ◽  
Vol 01 (02) ◽  
pp. 108-120 ◽  
Author(s):  
Nick Lane
Keyword(s):  
Protein Synthesis ◽  
Host Cell ◽  
Genome Size ◽  
Energy Savings ◽  
Nuclear Genome ◽  
Eukaryotic Cell ◽  
Eukaryotic Cells ◽  
Bacterial Genomes ◽  
Complex Cells ◽  
Life On Earth

All complex life on Earth is composed of ‘eukaryotic’ cells. Eukaryotes arose just once in 4 billion years, via an endosymbiosis — bacteria entered a simple host cell, evolving into mitochondria, the ‘powerhouses’ of complex cells. Mitochondria lost most of their genes, retaining only those needed for respiration, giving eukaryotes ‘multi-bacterial’ power without the costs of maintaining thousands of complete bacterial genomes. These energy savings supported a substantial expansion in nuclear genome size, and far more protein synthesis from each gene.

scholarly journals Mitochondrial Protein Network: From Biogenesis to Bioenergetics in Health and Disease

2020 ◽  
Vol 22 (1) ◽  
pp. 1
Author(s):  
Alessandra Ferramosca
Keyword(s):  
Crucial Role ◽  
Mitochondrial Protein ◽  
Protein Network ◽  
Eukaryotic Cells ◽  
Double Membrane ◽  
Health And Disease ◽  
Membrane Bound

Mitochondria are double membrane-bound organelles which are essential for the viability of eukaryotic cells, because they play a crucial role in bioenergetics, metabolism and signaling [...]

Functions of selected biochemical systems from the exercised-trained dog heart

1977 ◽  
Vol 42 (3) ◽  
pp. 426-431 ◽  
Author(s):  
L. A. Sordahl ◽  
G. K. Asimakis ◽  
R. T. Dowell ◽  
H. L. Stone
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Transport ◽  
Calcium Uptake ◽  
Atp Synthesis ◽  
Myocardial Cell ◽  
Ruthenium Red ◽  
Mitochondrial Membranes ◽  
Sedentary Control ◽  
Isolated Mitochondria ◽  
Biochemical Systems

Mitochondria and sarcoplasmic reticulum (SR) fractions were isolated from exercised-trained (E-T) and sedentary control dog hearts. Measurements of mitochondrial respiratory functions indicated no changes in energy-producing (ATP synthesis) capacity in mitochondria from E-T compared to control dog hearts. However, the ability of isolated mitochondria from E-T hearts to retain accumulated calcium was markedly decreased compared to controls. Inhibition of mitochondrial rates of calcium uptake with the inhibitor, ruthenium red, revealed fewer binding and/or transport sites in mitochondrial membranes from exercised-trained heart preparations. ATP-dependent binding (- oxalate) and uptake (+ oxalate) of calcium by SR preparations from E-T hearts were unchanged compared to controls. In contrast, significant differences in the rates of release of bound calcium were found in SR isolated from E-T hearts. Total myocardial protein, nucleic acids, and connective tissue levels were unchanged in E-T hearts compared to controls. The results suggest subtle changes are occurring in the energy-utilizing mechanism(s) involving calcium transport of the myocardial cell during exercise training. These changes may be related to alterations in the performance of the exercised-trained heart.

scholarly journals Conflict and cooperation in eukaryogenesis: implications for the timing of endosymbiosis and the evolution of sex

2015 ◽  
Author(s):  
Arunas L Radzvilavicius ◽  
Neil W Blackstone
Keyword(s):  
Cell Fusion ◽  
Mitochondrial Gene ◽  
Evolutionary Process ◽  
Eukaryotic Cell ◽  
Evolutionary Transition ◽  
Evolutionary Transitions ◽  
Conflict And Cooperation ◽  
Conflict Mediation ◽  
Considerable Debate ◽  
History Of

The complex eukaryotic cell is a result of an ancient endosymbiosis and one of the major evolutionary transitions. The timing of key eukaryotic innovations relative to the acquisition of mitochondria remains subject to considerable debate, yet the evolutionary process itself might constrain the order of these events. Endosymbiosis entailed levels-of-selection conflicts, and mechanisms of conflict mediation had to evolve for eukaryogenesis to proceed. The initial mechanisms of conflict mediation were based on the pathways inherited from prokaryotic symbionts and led to metabolic homeostasis in the eukaryotic cell, while later mechanisms (e.g., mitochondrial gene transfer) contributed to the expansion of the eukaryotic genome. Perhaps the greatest opportunity for conflict arose with the emergence of sex involving whole-cell fusion. While early evolution of cell fusion may have affected symbiont acquisition, sex together with the competitive symbiont behaviour would have destabilised the emerging higher-level unit. Cytoplasmic mixing, on the other hand, would have been beneficial for selfish endosymbionts, capable of using their own metabolism to manipulate the life history of the host. Given the results of our mathematical modelling, we argue that sex represents a rather late proto- eukaryotic innovation, allowing for the growth of the chimeric nucleus and contributing to the successful completion of the evolutionary transition.

scholarly journals Bacterial tail anchors can target to the mitochondrial outer membrane

2017 ◽  
Author(s):  
Güleycan Lutfullahoğlu Bal ◽  
Abdurrahman Keskin ◽  
Ayşe Bengisu Seferoğlu ◽  
Cory D. Dunn
Keyword(s):  
Outer Membrane ◽  
Protein Translocation ◽  
Mitochondrial Protein ◽  
Eukaryotic Cell ◽  
Eukaryotic Cells ◽  
Mitochondrial Outer Membrane ◽  
Bacterial Proteins ◽  
Rate Limiting Step ◽  
Protein Entry ◽  
Rate Limiting

ABSTRACTDuring the generation and evolution of the eukaryotic cell, a proteobacterial endosymbiont was refashioned into the mitochondrion, an organelle that appears to have been present in the ancestor of all present-day eukaryotes. Mitochondria harbor proteomes derived from coding information located both inside and outside the organelle, and the rate-limiting step toward the formation of eukaryotic cells may have been development of an import apparatus allowing protein entry to mitochondria. Currently, a widely conserved translocon allows proteins to pass from the cytosol into mitochondria, but how proteins encoded outside of mitochondria were first directed to these organelles at the dawn of eukaryogenesis is not clear. Because several proteins targeted by a carboxyl-terminal tail anchor (TA) appear to have the ability to insert spontaneously into the mitochondrial outer membrane (OM), it is possible that self-inserting, tail-anchored polypeptides obtained from bacteria might have formed the first gate allowing proteins to access mitochondria from the cytosol. Here, we tested whether bacterial TAs are capable of targeting to mitochondria. In a survey of proteins encoded by the proteobacterium Escherichia coli, predicted TA sequences were directed to specific subcellular locations within the yeast Saccharomyces cerevisiae. Importantly, TAs obtained from DUF883 family members ElaB and YqjD were abundantly localized to and inserted at the mitochondrial OM. Our results support the notion that eukaryotic cells are able to utilize membrane-targeting signals present in bacterial proteins obtained by lateral gene transfer, and our findings make plausible a model in which mitochondrial protein translocation was first driven by tail-anchored proteins.

Pyrophosphate as an alternative energy currency in plants

2021 ◽  
Vol 478 (8) ◽  
pp. 1515-1524
Author(s):  
Abir U. Igamberdiev ◽  
Leszek A. Kleczkowski
Keyword(s):  
Metabolic Pathways ◽  
Energy Efficient ◽  
Alternative Energy ◽  
Plant Cells ◽  
Atp Synthesis ◽  
Continuous Operation ◽  
Low Oxygen ◽  
Pyruvate Phosphate Dikinase ◽  
Oxygen Stress ◽  
Membrane Bound

In the conditions of [Mg2+] elevation that occur, in particular, under low oxygen stress and are the consequence of the decrease in [ATP] and increase in [ADP] and [AMP], pyrophosphate (PPi) can function as an alternative energy currency in plant cells. In addition to its production by various metabolic pathways, PPi can be synthesized in the combined reactions of pyruvate, phosphate dikinase (PPDK) and pyruvate kinase (PK) by so-called PK/PPDK substrate cycle, and in the reverse reaction of membrane-bound H+-pyrophosphatase, which uses the energy of electrochemical gradients generated on tonoplast and plasma membrane. The PPi can then be consumed in its active forms of MgPPi and Mg2PPi by PPi-utilizing enzymes, which require an elevated [Mg2+]. This ensures a continuous operation of glycolysis in the conditions of suppressed ATP synthesis, keeping metabolism energy efficient and less dependent on ATP.

scholarly journals Listeria monocytogenes Possesses Adhesins for Fibronectin

1999 ◽  
Vol 67 (12) ◽  
pp. 6698-6701 ◽  
Author(s):  
Philippe Gilot ◽  
Paul André ◽  
Jean Content
Keyword(s):  
Extracellular Matrix ◽  
Listeria Monocytogenes ◽  
Cell Surface ◽  
Bacterial Cell ◽  
Cell Types ◽  
Eukaryotic Cell ◽  
Eukaryotic Cells ◽  
Food Borne ◽  
Human Fibronectin ◽  
Fibronectin Binding

ABSTRACT Listeria monocytogenes is a gram-positive, nonsporulating, food-borne pathogen of humans and animals that is able to invade many eukaryotic cells. Several listerial surface components have been reported to interact with eukaryotic cell receptors, but the complete mechanism by which the bacteria interact with all of these cell types remains largely unknown. In this work, we found thatL. monocytogenes binds to human fibronectin, a 450,000-Da dimeric glycoprotein found in body fluids, on the surface of cells and in an insoluble component of the extracellular matrix. The binding of fibronectin to L. monocytogenes was found to be saturable and dependent on proteinaceous receptors. Five fibronectin-binding proteins of 55.3, 48.6, 46.7, 42.4, and 26.8 kDa were identified. The 55.3-kDa protein was proved to be present at the bacterial cell surface. The binding of L. monocytogenes to fibronectin adds to the number of molecules to which the bacterium is able to adhere and emphasizes the complexity of host-pathogen interactions.

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