Porins in mitochondria

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Federal government websites often end in. The site is secure. Preview improvements coming to the PMC website in October Learn More or Try it out now. Mitochondrial porins, or voltage-dependent anion-selective channels VDAC allow the passage of small molecules across the mitochondrial outer membrane, and are involved in complex interactions regulating organellar and cellular metabolism. Numerous organisms possess multiple porin isoforms, and initial studies indicated an intriguing evolutionary history for these proteins and the genes that encode them. In this work, the wealth of recent sequence information was used to perform a comprehensive analysis of the evolutionary history of mitochondrial porins.

Porins in mitochondria

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. 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. 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 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. The age of earth is around 4.

Analysis of the aligned regions encompassing the eukaryotic signature motif did not reveal porins in mitochondria motif common to all eukaryotic porins; this finding is not surprising given the low degree of sequence identity across the spectrum of sequences analyzed herein.

Mitochondria import the vast majority of their proteins via dedicated protein machineries. The translocase of the outer membrane TOM complex forms the main entry site for precursor proteins that are produced on cytosolic ribosomes. Subsequently, different protein sorting machineries transfer the incoming preproteins to the mitochondrial outer and inner membranes, the intermembrane space, and the matrix. In this review, we highlight the recently discovered role of porin, also termed voltage-dependent anion channel VDAC , in mitochondrial protein biogenesis. Porin forms the major channel for metabolites and ions in the outer membrane of mitochondria.

Metrics details. Mitochondrial porins, or voltage-dependent anion-selective channels VDAC allow the passage of small molecules across the mitochondrial outer membrane, and are involved in complex interactions regulating organellar and cellular metabolism. Numerous organisms possess multiple porin isoforms, and initial studies indicated an intriguing evolutionary history for these proteins and the genes that encode them. In this work, the wealth of recent sequence information was used to perform a comprehensive analysis of the evolutionary history of mitochondrial porins. Fungal porin sequences were well represented, and newly-released sequences from stramenopiles, alveolates, and seed and flowering plants were analyzed. A combination of Neighbour-Joining and Bayesian methods was used to determine phylogenetic relationships among the proteins. The aligned sequences were also used to reassess the validity of previously described eukaryotic porin motifs and to search for signature sequences characteristic of VDACs from plants, animals and fungi. Secondary structure predictions were performed on the aligned VDAC primary sequences and were used to evaluate the sites of intron insertion in a representative set of the corresponding VDAC genes. Our phylogenetic analysis clearly shows that paralogs have appeared several times during the evolution of VDACs from the plants, metazoans, and even the fungi, suggesting that there are no "ancient" paralogs within the gene family. Sequence motifs characteristic of the members of the crown groups of organisms were identified.

Porins in mitochondria

Federal government websites often end in. The site is secure. 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. 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. 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 sequences of eukaryotic porins are known to date.

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Updated sequence information may resolve this issue, as the B. Benz Wiley-VCh: Weinheim , — As a library, NLM provides access to scientific literature. Webb, C. Voltage-dependent anion channels: the wizard of the mitochondrial outer membrane. Alterations to the wild-type sequence are indicated in bold. Blachly-Dyson et al. Kovermann, P. Deletion of voltage-dependent anion channel 1 knocks mitochondrial down triggering metabolic rewiring in yeast. Distributed by the author. We conclude that BN-PAGE of digitonin-lysed mitochondria represents a specific assay to determine correct import and assembly of porin in yeast. Exploring the role of the histidine biosynthetic hisF gene in cellular metabolism and in the evolution of ancestral genes: from LUCA to the extant micro organisms.

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Transport of proteins into mitochondria. Reconstitution in planar lipid bilayers of a voltage-dependent anion-selective channel obtained from paramecium mitochondria. Following the renaturation process of different eukaryotic porins, it seems that sterols seem to be necessary, although they may modulate the properties of the pores, in particular of plant porins Popp et al. The crystal structure of mouse VDAC1 at 2. EMBO J. P G is the probability for the occurrence of a conductance step with a certain single-channel conductance given in nS. In the fungi and animals, the VDAC sequences lacking this motif are scattered throughout the phylogenetic tree, and there is no apparent link between the presence of this motif and the eukaryotic signature sequence. However, due to selective pressure, bacteria can develop resistance through mutations in the porin gene. An exception is Drosophila spp. Import of porin is not affected in tom mutant mitochondria.