scholarly journals Conserved structural elements specialize ATAD1 as a membrane protein extraction machine

2021 ◽  
Author(s):  
Lan Wang ◽  
Hannah Toutkoushian ◽  
Vladislav Belyy ◽  
Claire Kokontis ◽  
Peter Walter
Keyword(s):  
Amino Acids ◽  
Membrane Proteins ◽  
Protein Import ◽  
Protein Extraction ◽  
Structural Features ◽  
Live Cells ◽  
Mitochondrial Outer Membrane ◽  
Structural Elements ◽  
Peptide Substrate ◽  
Hydrophobic Membrane

AbstractThe mitochondrial AAA protein ATAD1 (in humans; Msp1 in yeast) removes mislocalized membrane proteins, as well as stuck import substrates from the mitochondrial outer membrane, facilitating their re-insertion into their cognate organelles and maintaining mitochondria’s protein import capacity. In doing so, it helps to maintain proteostasis in mitochondria. How ATAD1 tackles the energetic challenge to extract hydrophobic membrane proteins from the lipid bilayer and what structural features adapt ATAD1 for its particular function has remained a mystery. Previously, we determined the structure of Msp1 in complex with a peptide substrate (Wang et al., 2020). The structure showed that Msp1’s mechanism follows the general principle established for AAA proteins while adopting several structural features that specialize it for its function. We used the yeast growth assay to test the function of key amino acids within these structural elements. In this work, we determined the cryo-EM structures of the human ATAD1 in complex with a peptide substrate at near atomic resolution. The structures show that phylogenetically conserved structural elements adapt ATAD1 for its function while generally adopting a conserved mechanism shared by many AAA proteins. ATAD1’s distinguishing features include an abundance of aromatic amino acids that line the central pore proposed to give ATAD1 a firm grip on its substrate and a short α-helix at the C-terminus that strongly facilitates ATAD1’s oligomerization. We also developed a microscopy-based assay reporting on protein mislocalization, with which we directly assessed ATAD1’s activity in live cells.

Biogenesis pathways of α-helical mitochondrial outer membrane proteins

2020 ◽  
Vol 401 (6-7) ◽  
pp. 677-686 ◽  
Author(s):  
Layla Drwesh ◽  
Doron Rapaport
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Protein Import ◽  
Nuclear Dna ◽  
Current Knowledge ◽  
Outer Membrane Proteins ◽  
Mitochondrial Outer Membrane ◽  
Cytosolic Ribosomes

AbstractMitochondria harbor in their outer membrane (OM) proteins of different topologies. These proteins are encoded by the nuclear DNA, translated on cytosolic ribosomes and inserted into their target organelle by sophisticated protein import machineries. Recently, considerable insights have been accumulated on the insertion pathways of proteins into the mitochondrial OM. In contrast, little is known regarding the early cytosolic stages of their biogenesis. It is generally presumed that chaperones associate with these proteins following their synthesis in the cytosol, thereby keeping them in an import-competent conformation and preventing their aggregation and/or mis-folding and degradation. In this review, we outline the current knowledge about the biogenesis of different mitochondrial OM proteins with various topologies, and highlight the recent findings regarding their import pathways starting from early cytosolic events until their recognition on the mitochondrial surface that lead to their final insertion into the mitochondrial OM.

Proto-oncogene c-ros codes for a molecule with structural features common to those of growth factor receptors and displays tissue specific and developmentally regulated expression

1986 ◽  
Vol 6 (5) ◽  
pp. 1478-1486
Author(s):  
W S Neckameyer ◽  
M Shibuya ◽  
M T Hsu ◽  
L H Wang
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Growth Factor ◽  
Kidney Tissue ◽  
Growth Factor Receptors ◽  
Structural Features ◽  
Amino Acid Sequences ◽  
Nucleotide Sequencing ◽  
Hydrophobic Membrane ◽  
Hydrophobic Domain

A recombinant DNA clone containing cellular sequences homologous to the transforming sequence, v-ros, of avian sarcoma virus UR2 was isolated from a chicken genomic DNA library. Heteroduplex mapping and nucleotide sequencing reveal that the v-ros sequences are distributed in nine exons ranging from 65 to 204 nucleotides on cellular ros (c-ros) DNA over a range of 11 kilobases. Comparison of the deduced amino acid sequences of c-ros and v-ros shows two differences: v-ros contains a three-amino-acid insertion within the hydrophobic domain presumed to be involved in membrane association, and (ii) the carboxyl 12 amino acids of v-ros are completely different from those of the deduced c-ros sequence. The deduced amino acid sequence of c-ros bears striking structural features similar to those of insulin and epidermal growth factor receptors, including the presumed hydrophobic membrane binding domain, amino acids flanking the domain, and the distance between the domain and the catalytic region of the kinase activity. The expression of c-ros appears to be under a very stringent control. When tissues at various stages of chicken development were analyzed, only kidney was found to contain a significant level of c-ros RNA. The level of c-ros RNA in kidney tissue is most abundant in 7- to 14-day-old chickens. Finally, nucleotide sequences of c-ros DNA and UR2-associated helper viral genome at regions corresponding to the gag ros recombination site suggest that the junction has been formed by RNA splicing.

scholarly journals Structural Insight into Mitochondrial β-Barrel Outer Membrane Protein Biogenesis

2020 ◽  
Author(s):  
Kathryn A. Diederichs ◽  
Xiaodan Ni ◽  
Sarah E. Rollauer ◽  
Istvan Botos ◽  
Xiaofeng Tan ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Protein Import ◽  
Sequence Similarity ◽  
Outer Membrane Proteins ◽  
Complex Structure ◽  
Mitochondrial Outer Membrane ◽  
Intermembrane Space ◽  
Cytosolic Side ◽  
Lateral Gate

AbstractIn mitochondria, β-barrel outer membrane proteins mediate protein import, metabolite transport, lipid transport, and biogenesis. The Sorting and Assembly Machinery (SAM) complex consists of three proteins that assemble as a 1:1:1 complex to fold β-barrel proteins and insert them into the mitochondrial outer membrane. We report cryoEM structures of the SAM complex from Myceliophthora thermophila, which show that Sam50 forms a 16-stranded transmembrane β-barrel with a single polypeptide-transport-associated (POTRA) domain extending into the intermembrane space. Sam35 and Sam37 are located on the cytosolic side of the outer membrane, with Sam35 capping Sam50, and Sam37 interacting extensively with Sam35. Sam35 and Sam37 each adopt a GST-like fold, with no functional, structural, or sequence similarity to their bacterial counterparts. Structural analysis shows how the Sam50 β-barrel opens a lateral gate to accommodate its substrates. The SAM complex structure suggests how it interacts with other mitochondrial outer membrane proteins to create supercomplexes.

scholarly journals Proto-oncogene c-ros codes for a molecule with structural features common to those of growth factor receptors and displays tissue specific and developmentally regulated expression.

1986 ◽  
Vol 6 (5) ◽  
pp. 1478-1486 ◽  
Author(s):  
W S Neckameyer ◽  
M Shibuya ◽  
M T Hsu ◽  
L H Wang
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Growth Factor ◽  
Kidney Tissue ◽  
Growth Factor Receptors ◽  
Structural Features ◽  
Amino Acid Sequences ◽  
Nucleotide Sequencing ◽  
Hydrophobic Membrane ◽  
Hydrophobic Domain

A recombinant DNA clone containing cellular sequences homologous to the transforming sequence, v-ros, of avian sarcoma virus UR2 was isolated from a chicken genomic DNA library. Heteroduplex mapping and nucleotide sequencing reveal that the v-ros sequences are distributed in nine exons ranging from 65 to 204 nucleotides on cellular ros (c-ros) DNA over a range of 11 kilobases. Comparison of the deduced amino acid sequences of c-ros and v-ros shows two differences: v-ros contains a three-amino-acid insertion within the hydrophobic domain presumed to be involved in membrane association, and (ii) the carboxyl 12 amino acids of v-ros are completely different from those of the deduced c-ros sequence. The deduced amino acid sequence of c-ros bears striking structural features similar to those of insulin and epidermal growth factor receptors, including the presumed hydrophobic membrane binding domain, amino acids flanking the domain, and the distance between the domain and the catalytic region of the kinase activity. The expression of c-ros appears to be under a very stringent control. When tissues at various stages of chicken development were analyzed, only kidney was found to contain a significant level of c-ros RNA. The level of c-ros RNA in kidney tissue is most abundant in 7- to 14-day-old chickens. Finally, nucleotide sequences of c-ros DNA and UR2-associated helper viral genome at regions corresponding to the gag ros recombination site suggest that the junction has been formed by RNA splicing.

scholarly journals Insertion of plastidic β-barrel proteins into the outer envelopes of plastids involves an intermembrane space intermediate formed with Toc75-V/OEP80

2021 ◽  
Author(s):  
Lucia E Gross ◽  
Anna Klinger ◽  
Nicole Spies ◽  
Theresa Ernst ◽  
Nadine Flinner ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Protein Import ◽  
Membrane Insertion ◽  
Intermembrane Space ◽  
Envelope Membrane ◽  
Outer Envelope ◽  
Pea Proteins ◽  
Outer Envelope Membrane ◽  
Correct Topology ◽  
Shed Light

Abstract The insertion of organellar membrane proteins with the correct topology requires the following: First, the proteins must contain topogenic signals for translocation across and insertion into the membrane. Second, proteinaceous complexes in the cytoplasm, membrane, and lumen of organelles are required to drive this process. Many complexes required for the intracellular distribution of membrane proteins have been described, but the signals and components required for the insertion of plastidic β-barrel-type proteins into the outer membrane are largely unknown. The discovery of common principles is difficult, as only a few plastidic β-barrel proteins exist. Here, we provide evidence that the plastidic outer envelope β-barrel proteins OEP21, OEP24, and OEP37 from pea (Pisum sativum) and Arabidopsis thaliana contain information defining the topology of the protein. The information required for translocation of pea proteins across the outer envelope membrane is present within the six N-terminal β-strands. This process requires the action of TOC (translocon of the outer chloroplast membrane). After translocation into the intermembrane space, β-barrel proteins interact with TOC75-V, as exemplified by OEP37 and P39, and are integrated into the membrane. The membrane insertion of plastidic β-barrel proteins is affected by mutation of the last β-strand, suggesting that this strand contributes to the insertion signal. These findings shed light on the elements and complexes involved in plastidic β-barrel protein import.

scholarly journals TOM20-mediated transfer of Bcl2 from ER to MAM and mitochondria upon induction of apoptosis

2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Lisenn Lalier ◽  
Vincent Mignard ◽  
Marie-Pierre Joalland ◽  
Didier Lanoé ◽  
Pierre-François Cartron ◽  
...  
Keyword(s):  
Protein Import ◽  
Glioma Cells ◽  
Mitochondrial Outer Membrane ◽  
Mitochondrial Localization ◽  
Antiapoptotic Protein ◽  
Mitochondrial Transfer ◽  
Small Domain ◽  
Induction Of Apoptosis ◽  
And Function

AbstractIn this work, we have explored the subcellular localization of Bcl2, a major antiapoptotic protein. In U251 glioma cells, we found that Bcl2 is localized mainly in the ER and is translocated to MAM and mitochondria upon induction of apoptosis; this mitochondrial transfer was not restricted to the demonstrator cell line, even if cell-specific modulations exist. We found that the Bcl2/mitochondria interaction is controlled by TOM20, a protein that belongs to the protein import machinery of the mitochondrial outer membrane. The expression of a small domain of interaction of TOM20 with Bcl2 potentiates its anti-apoptotic properties, which suggests that the Bcl2–TOM20 interaction is proapoptotic. The role of MAM and TOM20 in Bcl2 apoptotic mitochondrial localization and function has been confirmed in a yeast model in which the ER–mitochondria encounter structure (ERMES) complex (required for MAM stability in yeast) has been disrupted. Bcl2–TOM20 interaction is thus an additional player in the control of apoptosis.

scholarly journals Role of Phosphatidylethanolamine in the Biogenesis of Mitochondrial Outer Membrane Proteins

2013 ◽  
Vol 288 (23) ◽  
pp. 16451-16459 ◽  
Author(s):  
Thomas Becker ◽  
Susanne E. Horvath ◽  
Lena Böttinger ◽  
Natalia Gebert ◽  
Günther Daum ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Proper Function ◽  
Mitochondrial Outer Membrane ◽  
Tom Complex ◽  
Precursor Proteins ◽  
Helical Proteins ◽  
The Stability

The mitochondrial outer membrane contains proteinaceous machineries for the import and assembly of proteins, including TOM (translocase of the outer membrane) and SAM (sorting and assembly machinery). It has been shown that the dimeric phospholipid cardiolipin is required for the stability of TOM and SAM complexes and thus for the efficient import and assembly of β-barrel proteins and some α-helical proteins of the outer membrane. Here, we report that mitochondria deficient in phosphatidylethanolamine (PE), the second non-bilayer-forming phospholipid, are impaired in the biogenesis of β-barrel proteins, but not of α-helical outer membrane proteins. The stability of TOM and SAM complexes is not disturbed by the lack of PE. By dissecting the import steps of β-barrel proteins, we show that an early import stage involving translocation through the TOM complex is affected. In PE-depleted mitochondria, the TOM complex binds precursor proteins with reduced efficiency. We conclude that PE is required for the proper function of the TOM complex.

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