scholarly journals p166 links membrane and intramitochondrial modules of the trypanosomal tripartite attachment complex

2021 ◽  
Author(s):  
Bernd Schimanski ◽  
Salome Aeschlimann ◽  
Sandro Käser ◽  
Maria Gomez-Fabra Gala ◽  
Nora Vögtle ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Transmembrane Domain ◽  
Proper Function ◽  
Intermembrane Space ◽  
Kinetoplast Dna ◽  
Mitochondrial Membranes ◽  
Inner Membrane ◽  
Large N ◽  
Associated Proteins ◽  
Single Mitochondrion

The protist parasite Trypanosoma brucei has a single mitochondrion with a single unit genome termed kinetoplast DNA (kDNA). Faithfull segregation of replicated kDNA is ensured by a complicated structure termed tripartite attachment complex (TAC). The TAC physically links the basal body of the flagellum with the kDNA spanning the two mitochondrial membranes. Here, we characterized p166 as the only TAC subunit that is anchored in the inner membrane. Its C-terminal transmembrane domain separates the protein into a large N-terminal region that interacts with the kDNA-localized TAC102 and a 34 aa C-tail that binds to the intermembrane space-exposed loop of the integral outer membrane protein TAC60. Thus, in contrast to the outer membrane TAC region which requires four essential subunits for proper function a single inner membrane TAC subunit is sufficient to bridge the distance from the OM to the kDNA. Surprisingly, non-functional p166 lacking the C-terminal 34 aa still localizes to the TAC region. This suggests the existence of nonessential TAC-associated proteins in the OM. These proteins can loosely bind to non-functional p166 lacking the C-terminal 34 aa and keep it at the TAC but their binding would not be strong enough to withstand the mechanical force upon kDNA segregation.

scholarly journals Coassembly of Mgm1 isoforms requires cardiolipin and mediates mitochondrial inner membrane fusion

2009 ◽  
Vol 186 (6) ◽  
pp. 793-803 ◽  
Author(s):  
Rachel M. DeVay ◽  
Lenin Dominguez-Ramirez ◽  
Laura L. Lackner ◽  
Suzanne Hoppins ◽  
Henning Stahlberg ◽  
...  
Keyword(s):  
Membrane Fusion ◽  
Coiled Coil ◽  
Intermembrane Space ◽  
Dependent Manner ◽  
Related Protein ◽  
Mitochondrial Membranes ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
N Terminus ◽  
In Trans

Two dynamin-related protein (DRP) families are essential for fusion of the outer and inner mitochondrial membranes, Fzo1 (yeast)/Mfn1/Mfn2 (mammals) and Mgm1 (yeast)/Opa1 (mammals), respectively. Fzo1/Mfns possess two medial transmembrane domains, which place their critical GTPase and coiled-coil domains in the cytosol. In contrast, Mgm1/Opa1 are present in cells as long (l) isoforms that are anchored via the N terminus to the inner membrane, and short (s) isoforms were predicted to be soluble in the intermembrane space. We addressed the roles of Mgm1 isoforms and how DRPs function in membrane fusion. Our analysis indicates that in the absence of a membrane, l- and s-Mgm1 both exist as inactive GTPase monomers, but that together in trans they form a functional dimer in a cardiolipin-dependent manner that is the building block for higher-order assemblies.

scholarly journals Role of the intermembrane-space domain of the preprotein receptor Tom22 in protein import into mitochondria.

1996 ◽  
Vol 16 (8) ◽  
pp. 4035-4042 ◽  
Author(s):  
D A Court ◽  
F E Nargang ◽  
H Steiner ◽  
R S Hodges ◽  
W Neupert ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Protein Import ◽  
Protein Translocation ◽  
Specific Binding ◽  
Mitochondrial Outer Membrane ◽  
Intermembrane Space ◽  
Inner Membrane ◽  
Terminal Domain ◽  
Tom Complex

Tom22 is an essential component of the protein translocation complex (Tom complex) of the mitochondrial outer membrane. The N-terminal domain of Tom22 functions as a preprotein receptor in cooperation with Tom20. The role of the C-terminal domain of Tom22, which is exposed to the intermembrane space (IMS), in its own assembly into the Tom complex and in the import of other preproteins was investigated. The C-terminal domain of Tom22 is not essential for the targeting and assembly of this protein, as constructs lacking part or all of the IMS domain became imported into mitochondria and assembled into the Tom complex. Mutant strains of Neurospora expressing the truncated Tom22 proteins were generated by a novel procedure. These mutants displayed wild-type growth rates, in contrast to cells lacking Tom22, which are not viable. The import of proteins into the outer membrane and the IMS of isolated mutant mitochondria was not affected. Some but not all preproteins destined for the matrix and inner membrane were imported less efficiently. The reduced import was not due to impaired interaction of presequences with their specific binding site on the trans side of the outer membrane. Rather, the IMS domain of Tom22 appears to slightly enhance the efficiency of the transfer of these preproteins to the import machinery of the inner membrane.

Multiple pathways for mitochondrial protein traffic

2009 ◽  
Vol 390 (8) ◽  
Author(s):  
Toshiya Endo ◽  
Koji Yamano
Keyword(s):  
Outer Membrane ◽  
Protein Trafficking ◽  
Protein Import ◽  
Mitochondrial Protein ◽  
Intermembrane Space ◽  
Mitochondrial Protein Import ◽  
Inner Membrane ◽  
Protein Traffic

Abstract Mitochondria are two-membrane bounded organelles consisting of 1000–2000 different proteins, most of which are synthesized in the cytosol and subsequently imported into mitochondria. The imported proteins are further sorted to one of the four compartments, the outer membrane, intermembrane space, inner membrane, and matrix, mostly following one of the five major pathways. Mitochondrial protein import and sorting are mediated by the translocator complexes in the membranes and chaperones in the aqueous compartments operating along the import pathways. Here, we summarize the expanding knowledge on the roles of translocators, chaperones, and related components in the multiple pathways for mitochondrial protein trafficking.

scholarly journals The Landscape of Pseudomonas aeruginosa Membrane-Associated Proteins

Cells ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 2421
Author(s):  
Sara Motta ◽  
Davide Vecchietti ◽  
Alessandra M. Martorana ◽  
Pietro Brunetti ◽  
Giovanni Bertoni ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Outer Membrane ◽  
Protein Identification ◽  
Bacterial Species ◽  
Outer Membrane Proteins ◽  
Protein Domains ◽  
Host Cells ◽  
Inner Membrane ◽  
Proteomic Data ◽  
Associated Proteins

Background: Pseudomonas aeruginosa cell envelope-associated proteins play a relevant role in infection mechanisms. They can contribute to the antibiotic resistance of the bacterial cells and be involved in the interaction with host cells. Thus, studies contributing to elucidating these key molecular elements are of great importance to find alternative therapeutics. Methods: Proteins and peptides were extracted by different methods and analyzed by Multidimensional Protein Identification Technology (MudPIT) approach. Proteomic data were processed by Discoverer2.1 software and multivariate statistics, i.e., Linear Discriminant Analysis (LDA), while the Immune Epitope Database (IEDB) resources were used to predict antigenicity and immunogenicity of experimental identified peptides and proteins. Results: The combination of 29 MudPIT runs allowed the identification of 10,611 peptides and 2539 distinct proteins. Following application of extraction methods enriching specific protein domains, about 15% of total identified peptides were classified in trans inner-membrane, inner-membrane exposed, trans outer-membrane and outer-membrane exposed. In this scenario, nine outer membrane proteins (OprE, OprI, OprF, OprD, PagL, OprG, PA1053, PAL and PA0833) were predicted to be highly antigenic. Thus, they were further processed and epitopes target of T cells (MHC Class I and Class II) and B cells were predicted. Conclusion: The present study represents one of the widest characterizations of the P. aeruginosa membrane-associated proteome. The feasibility of our method may facilitates the investigation of other bacterial species whose envelope exposed protein domains are still unknown. Besides, the stepwise prioritization of proteome, by combining experimental proteomic data and reverse vaccinology, may be useful for reducing the number of proteins to be tested in vaccine development.

scholarly journals Discrimination of distinct proteinases at the four structural levels of rat liver mitochondria

1986 ◽  
Vol 233 (1) ◽  
pp. 283-286 ◽  
Author(s):  
M C Duque-Magalhães ◽  
P Régnier
Keyword(s):  
Outer Membrane ◽  
Rat Liver ◽  
Degradation Products ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Intermembrane Space ◽  
Peptidase Activity ◽  
Inner Membrane ◽  
Mitochondrial Fractions ◽  
The Matrix

Rat liver mitochondrial fractions corresponding to four morphological structures (matrix, inner membrane, intermembrane space and outer membrane) contain proteinases that cleave casein components at different rates. Proteinases of the intermembrane space preferentially cleave kappa-casein, whereas the proteinases of the outer membrane, inner membrane and matrix fractions degrade alpha S1-casein more rapidly. Electrophoretic separation of the degradation products of alpha S1-casein and kappa-casein in polyacrylamide gels shows that different polypeptides are produced when the substrate is degraded by the matrix, by both membranes and by the intermembrane-space fraction. Some of the degradation products resulting from incubation of the caseins with the mitochondrial fractions are probably the result of digestion by contaminating lysosomal proteinase(s). The matrix has a high peptidase activity, since glucagon, a small peptide, is very rapidly degraded by this fraction. These observations strongly suggest that distinct proteinases, with different specificities, are associated respectively with the intermembrane space and with both membrane fractions.

scholarly journals Biogenesis of Mitochondrial Metabolite Carriers

Biomolecules ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1008 ◽  
Author(s):  
Patrick Horten ◽  
Lilia Colina-Tenorio ◽  
Heike Rampelt
Keyword(s):  
Outer Membrane ◽  
Mitochondrial Outer Membrane ◽  
Intermembrane Space ◽  
Inner Membrane ◽  
Chaperone Function ◽  
Mitochondrial Inner Membrane ◽  
Metabolic Reactions ◽  
Almost All ◽  
Related Proteins ◽  
Shed Light

Metabolite carriers of the mitochondrial inner membrane are crucial for cellular physiology since mitochondria contribute essential metabolic reactions and synthesize the majority of the cellular ATP. Like almost all mitochondrial proteins, carriers have to be imported into mitochondria from the cytosol. Carrier precursors utilize a specialized translocation pathway dedicated to the biogenesis of carriers and related proteins, the carrier translocase of the inner membrane (TIM22) pathway. After recognition and import through the mitochondrial outer membrane via the translocase of the outer membrane (TOM) complex, carrier precursors are ushered through the intermembrane space by hexameric TIM chaperones and ultimately integrated into the inner membrane by the TIM22 carrier translocase. Recent advances have shed light on the mechanisms of TOM translocase and TIM chaperone function, uncovered an unexpected versatility of the machineries, and revealed novel components and functional crosstalk of the human TIM22 translocase.

scholarly journals Mitochondria Use Different Mechanisms for Transport of Multispanning Membrane Proteins through the Intermembrane Space

2003 ◽  
Vol 23 (21) ◽  
pp. 7818-7828 ◽  
Author(s):  
Ann E. Frazier ◽  
Agnieszka Chacinska ◽  
Kaye N. Truscott ◽  
Bernard Guiard ◽  
Nikolaus Pfanner ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Heat Shock Protein 70 ◽  
Mitochondrial Outer Membrane ◽  
Intermembrane Space ◽  
Carrier Proteins ◽  
Inner Membrane ◽  
Tom Complex ◽  
Mitochondrial Inner Membrane ◽  
Integral Proteins ◽  
Matrix Heat

ABSTRACT The mitochondrial inner membrane contains numerous multispanning integral proteins. The precursors of these hydrophobic proteins are synthesized in the cytosol and therefore have to cross the mitochondrial outer membrane and intermembrane space to reach the inner membrane. While the import pathways of noncleavable multispanning proteins, such as the metabolite carriers, have been characterized in detail by the generation of translocation intermediates, little is known about the mechanism by which cleavable preproteins of multispanning proteins, such as Oxa1, are transferred from the outer membrane to the inner membrane. We have identified a translocation intermediate of the Oxa1 preprotein in the translocase of the outer membrane (TOM) and found that there are differences from the import mechanisms of carrier proteins. The intermembrane space domain of the receptor Tom22 supports the stabilization of the Oxa1 intermediate. Transfer of the Oxa1 preprotein to the inner membrane is not affected by inactivation of the soluble TIM complexes. Both the inner membrane potential and matrix heat shock protein 70 are essential to release the preprotein from the TOM complex, suggesting a close functional cooperation of the TOM complex and the presequence translocase of the inner membrane. We conclude that mitochondria employ different mechanisms for translocation of multispanning proteins across the aqueous intermembrane space.

scholarly journals The Oxidation Status of Mic19 Regulates MICOS Assembly

2015 ◽  
Vol 35 (24) ◽  
pp. 4222-4237 ◽  
Author(s):  
Paulina Sakowska ◽  
Daniel C. Jans ◽  
Karthik Mohanraj ◽  
Dietmar Riedel ◽  
Stefan Jakobs ◽  
...  
Keyword(s):  
Proper Function ◽  
Intermembrane Space ◽  
Inner Membrane ◽  
Content Type ◽  
Peripheral Protein ◽  
Membrane Morphology ◽  
Intramolecular Disulfide Bond ◽  
Oxidation Status ◽  
Mitochondrial Intermembrane Space ◽  
Redox Forms

The function of mitochondria depends on the proper organization of mitochondrial membranes. The morphology of the inner membrane is regulated by the recently identified mitochondrial contact site and crista organizing system (MICOS) complex. MICOS mutants exhibit alterations in crista formation, leading to mitochondrial dysfunction. However, the mechanisms that underlie MICOS regulation remain poorly understood. MIC19, a peripheral protein of the inner membrane and component of the MICOS complex, was previously reported to be required for the proper function of MICOS in maintaining the architecture of the inner membrane. Here, we show that human andSaccharomyces cerevisiaeMIC19 proteins undergo oxidation in mitochondria and require the mitochondrial intermembrane space assembly (MIA) pathway, which couples the oxidation and import of mitochondrial intermembrane space proteins for mitochondrial localization. Detailed analyses identified yeast Mic19 in two different redox forms. The form that contains an intramolecular disulfide bond is bound to Mic60 of the MICOS complex. Mic19 oxidation is not essential for its integration into the MICOS complex but plays a role in MICOS assembly and the maintenance of the proper inner membrane morphology. These findings suggest that Mic19 is a redox-dependent regulator of MICOS function.

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