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Benz R. Historical Perspective of Pore-Forming Activity Studies of Voltage-Dependent Anion Channel (Eukaryotic or Mitochondrial Porin) Since Its Discovery in the 70th of the Last Century. Front Physiol 2021; 12:734226. [PMID: 35547863 PMCID: PMC9083909 DOI: 10.3389/fphys.2021.734226] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 09/24/2021] [Indexed: 01/07/2023] Open
Abstract
Eukaryotic porin, also known as Voltage-Dependent Anion Channel (VDAC), is the most frequent protein in the outer membrane of mitochondria that are responsible for cellular respiration. Mitochondria are most likely descendants of strictly aerobic Gram-negative bacteria from the α-proteobacterial lineage. In accordance with the presumed ancestor, mitochondria are surrounded by two membranes. The mitochondrial outer membrane contains besides the eukaryotic porins responsible for its major permeability properties a variety of other not fully identified channels. It encloses also the TOM apparatus together with the sorting mechanism SAM, responsible for the uptake and assembly of many mitochondrial proteins that are encoded in the nucleus and synthesized in the cytoplasm at free ribosomes. The recognition and the study of electrophysiological properties of eukaryotic porin or VDAC started in the late seventies of the last century by a study of Schein et al., who reconstituted the pore from crude extracts of Paramecium mitochondria into planar lipid bilayer membranes. Whereas the literature about structure and function of eukaryotic porins was comparatively rare during the first 10years after the first study, the number of publications started to explode with the first sequencing of human Porin 31HL and the recognition of the important function of eukaryotic porins in mitochondrial metabolism. Many genomes contain more than one gene coding for homologs of eukaryotic porins. More than 100 sequences of eukaryotic porins are known to date. Although the sequence identity between them is relatively low, the polypeptide length and in particular, the electrophysiological characteristics are highly preserved. This means that all eukaryotic porins studied to date are anion selective in the open state. They are voltage-dependent and switch into cation-selective substates at voltages in the physiological relevant range. A major breakthrough was also the elucidation of the 3D structure of the eukaryotic pore, which is formed by 19 β-strands similar to those of bacterial porin channels. The function of the presumed gate an α-helical stretch of 20 amino acids allowed further studies with respect to voltage dependence and function, but its exact role in channel gating is still not fully understood.
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López-García P, Eme L, Moreira D. Symbiosis in eukaryotic evolution. J Theor Biol 2017; 434:20-33. [PMID: 28254477 DOI: 10.1016/j.jtbi.2017.02.031] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Revised: 02/19/2017] [Accepted: 02/25/2017] [Indexed: 01/27/2023]
Abstract
Fifty years ago, Lynn Margulis, inspiring in early twentieth-century ideas that put forward a symbiotic origin for some eukaryotic organelles, proposed a unified theory for the origin of the eukaryotic cell based on symbiosis as evolutionary mechanism. Margulis was profoundly aware of the importance of symbiosis in the natural microbial world and anticipated the evolutionary significance that integrated cooperative interactions might have as mechanism to increase cellular complexity. Today, we have started fully appreciating the vast extent of microbial diversity and the importance of syntrophic metabolic cooperation in natural ecosystems, especially in sediments and microbial mats. Also, not only the symbiogenetic origin of mitochondria and chloroplasts has been clearly demonstrated, but improvement in phylogenomic methods combined with recent discoveries of archaeal lineages more closely related to eukaryotes further support the symbiogenetic origin of the eukaryotic cell. Margulis left us in legacy the idea of 'eukaryogenesis by symbiogenesis'. Although this has been largely verified, when, where, and specifically how eukaryotic cells evolved are yet unclear. Here, we shortly review current knowledge about symbiotic interactions in the microbial world and their evolutionary impact, the status of eukaryogenetic models and the current challenges and perspectives ahead to reconstruct the evolutionary path to eukaryotes.
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Affiliation(s)
- Purificación López-García
- Ecologie Systématique Evolution, CNRS, Université Paris-Sud, Université Paris-Saclay, AgroParisTech, 91400 Orsay, France.
| | - Laura Eme
- Centre for Comparative Genomics and Evolutionary Bioinformatics, Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Canada NS B3H 4R2
| | - David Moreira
- Ecologie Systématique Evolution, CNRS, Université Paris-Sud, Université Paris-Saclay, AgroParisTech, 91400 Orsay, France
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Albarracín VH, Kurth D, Ordoñez OF, Belfiore C, Luccini E, Salum GM, Piacentini RD, Farías ME. High-Up: A Remote Reservoir of Microbial Extremophiles in Central Andean Wetlands. Front Microbiol 2015; 6:1404. [PMID: 26733008 PMCID: PMC4679917 DOI: 10.3389/fmicb.2015.01404] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Accepted: 11/25/2015] [Indexed: 11/18/2022] Open
Abstract
The Central Andes region displays unexplored ecosystems of shallow lakes and salt flats at mean altitudes of 3700 m. Being isolated and hostile, these so-called "High-Altitude Andean Lakes" (HAAL) are pristine and have been exposed to little human influence. HAAL proved to be a rich source of microbes showing interesting adaptations to life in extreme settings (poly-extremophiles) such as alkalinity, high concentrations of arsenic and dissolved salts, intense dryness, large daily ambient thermal amplitude, and extreme solar radiation levels. This work reviews HAAL microbiodiversity, taking into account different microbial niches, such as plankton, benthos, microbial mats and microbialites. The modern stromatolites and other microbialites discovered recently at HAAL are highlighted, as they provide unique modern-though quite imperfect-analogs of environments proxy for an earlier time in Earth's history (volcanic setting and profuse hydrothermal activity, low atmospheric O2 pressure, thin ozone layer and high UV exposure). Likewise, we stress the importance of HAAL microbes as model poly-extremophiles in the study of the molecular mechanisms underlying their resistance ability against UV and toxic or deleterious chemicals using genome mining and functional genomics. In future research directions, it will be necessary to exploit the full potential of HAAL poly-extremophiles in terms of their biotechnological applications. Current projects heading this way have yielded detailed molecular information and functional proof on novel extremoenzymes: i.e., DNA repair enzymes and arsenic efflux pumps for which medical and bioremediation applications, respectively, are envisaged. But still, much effort is required to unravel novel functions for this and other molecules that dwell in a unique biological treasure despite its being hidden high up, in the remote Andes.
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Affiliation(s)
- Virginia H. Albarracín
- Laboratorio de Investigaciones Microbiológicas de Lagunas Andinas, Planta Piloto de Procesos Industriales y Microbiológicos, Centro Científico Tecnológico, CONICETTucumán, Argentina
- Facultad de Ciencias Naturales e Instituto Miguel Lillo, Universidad Nacional de TucumánTucumán, Argentina
- Centro Integral de Microscopía Electrónica, Universidad Nacional de Tucumán, Centro Científico Tecnológico, CONICETTucumán, Argentina
| | - Daniel Kurth
- Laboratorio de Investigaciones Microbiológicas de Lagunas Andinas, Planta Piloto de Procesos Industriales y Microbiológicos, Centro Científico Tecnológico, CONICETTucumán, Argentina
| | - Omar F. Ordoñez
- Laboratorio de Investigaciones Microbiológicas de Lagunas Andinas, Planta Piloto de Procesos Industriales y Microbiológicos, Centro Científico Tecnológico, CONICETTucumán, Argentina
| | - Carolina Belfiore
- Laboratorio de Investigaciones Microbiológicas de Lagunas Andinas, Planta Piloto de Procesos Industriales y Microbiológicos, Centro Científico Tecnológico, CONICETTucumán, Argentina
| | - Eduardo Luccini
- CONICET Centro de Excelencia en Productos y Procesos de la Provincia de CórdobaCórdoba, Argentina
- Facultad de Química e Ingeniería, Pontificia Universidad Católica ArgentinaRosario, Argentina
| | - Graciela M. Salum
- Instituto de Física Rosario, CONICET Universidad Nacional de RosarioRosario, Argentina
- Facultad Regional Concepción del Uruguay, Universidad Tecnológica NacionalConcepción del Uruguay, Argentina
| | - Ruben D. Piacentini
- Facultad Regional Concepción del Uruguay, Universidad Tecnológica NacionalConcepción del Uruguay, Argentina
- Facultad de Ciencias Exactas, Ingeniería y Agrimensura, Universidad Nacional de RosarioRosario, Argentina
| | - María E. Farías
- Laboratorio de Investigaciones Microbiológicas de Lagunas Andinas, Planta Piloto de Procesos Industriales y Microbiológicos, Centro Científico Tecnológico, CONICETTucumán, Argentina
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Margulis L, Hinkle G, Stolz J, Craft F, Esteve I, Guerrero R. Mobilifilum chasei: morphology and ecology of a spirochete from an intertidal stratified microbial mat community. Arch Microbiol 2001; 153:422-7. [PMID: 11538692 DOI: 10.1007/bf00248421] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Spirochetes were found in the lower anoxiphototrophic layer of a stratified microbial mat (North Pond, Laguna Figueroa, Baja California, Mexico). Ultra-structural analysis of thin sections of field samples revealed spirochetes approximately 0.25 micrometer in diameter with 10 or more periplasmic flagella, leading to the interpretation that these spirochetes bear 10 flagellar insertions on each end. Morphometric study showed these free-living spirochetes greatly resemble certain symbiotic ones, i.e., Borrelia and certain termite spirochetes, the transverse sections of which are presented here. The ultrastructure of this spirochete also resembles Hollandina and Diplocalyx (spirochetes symbiotic in arthropods) more than it does Spirochaeta, the well known genus of mud-dwelling spirochetes. The new spirochete was detected in mat material collected both in 1985 and in 1987. Unique morphology (i.e., conspicuous outer coat of inner membrane, large number of periplasmic flagella) and ecology prompt us to name a new free-living spirochete.
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Affiliation(s)
- L Margulis
- Department of Botany, University of Massachusetts at Amherst 01003, USA
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Abstract
The distribution and types of microbial mats of the Ebro Delta (Catalonia, Spain) are described. The studied area is La Banya spit, formed by a narrow sand bar and a peninsula, located south of the main body of the Ebro Delta. Sea water can penetrate into the back shore through channel inlets, cutting the steeper coastal barrier of the open sea side of the spit or through the complex drainage channel system of the low-energy beaches in the inner Alfacs Bay. Sea water can stay in the back shore almost permanently, trapped in isolated depressions and lagoons. The surface distribution of microbial mats in La Banya spit has been studied by means of a detailed interpretation of vertical aerial photographs and field work consisting of mapping and sampling. The observed different ratios of cyanobacteria, as well as the presence and thickness of the layers of anoxygenic sulfur phototrophic bacteria, depend on the moisture content, the system stability, and the age of the microbial mat. Lyngbya, Oscillatoria, and Spirulina are the first cyanobacteria able to colonize the bare sediment. Lyngbya dominates in young microbial mats and in mats exposed to frequent desiccation. Microcoleus is the second most important colonist in the microbial succession. In relation to water, the alternation of emergence and submergence is optimal for the maximal development of Microcoleus-dominated microbial mats. We classify the microbial mats of the Ebro Delta into five main types: (i) Lyngbya-dominated type, in which the anoxygenic phototrophic bacteria are absent and the black layer of sulfate-reducers is very thin; (ii) Spirulina-dominated type; (iii) Oscillatoria-dominated type, which is found only at one site and covers a small area--this type, like the Spirulina-type mat, is not common in the Ebro Delta; (iv) Lyngbya/Microcoleus-transition type, in which Microcoleus and Lyngbya coexist in similar proportions--in the more developed mats of this group a layer of purple bacteria is usually present, and the black layer of sulfate-reducers is usually also well developed; and (v) Microcoleus-dominated type--in La Banya spit, this type is found in localities with relatively stable conditions. These areas are wet during most of the year. After appropriate conditions of diagenesis, the most highly developed microbial mats may be preserved as laminated hard sediments. The field study has been completed with cultivation, isolation, and identification of the main cyanobacterial genera under laboratory conditions.
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Affiliation(s)
- R Guerrero
- Department of Microbiology, University of Barcelona, Spain
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