Mitochondrial biogenesis: Protein import into and across the outer membrane

2004 ◽  
pp. 37-58 ◽  
Author(s):  
Doron Rapaport ◽  
Frank E. Nargang
Keyword(s):  
Outer Membrane ◽  
Mitochondrial Biogenesis ◽  
Protein Import

Contractile activity-induced adaptations in the mitochondrial protein import system

1998 ◽  
Vol 274 (5) ◽  
pp. C1380-C1387 ◽  
Author(s):  
Mark Takahashi ◽  
Alan Chesley ◽  
Damien Freyssenet ◽  
David A. Hood
Keyword(s):  
Outer Membrane ◽  
Malate Dehydrogenase ◽  
Mitochondrial Biogenesis ◽  
Protein Import ◽  
Contractile Activity ◽  
Mitochondrial Protein ◽  
Mitochondrial Protein Import ◽  
The Matrix ◽  
Stimulating Factor ◽  
Import Receptor

We previously demonstrated that subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondrial subfractions import proteins at different rates. This study was undertaken to investigate 1) whether protein import is altered by chronic contractile activity, which induces mitochondrial biogenesis, and 2) whether these two subfractions adapt similarly. Using electrical stimulation (10 Hz, 3 h/day for 7 and 14 days) to induce contractile activity, we observed that malate dehydrogenase import into the matrix of the SS and IMF mitochondia isolated from stimulated muscle was significantly increased by 1.4- to 1.7-fold, although the pattern of increase differed for each subfraction. This acceleration of import may be mitochondrial compartment specific, since the import of Bcl-2 into the outer membrane was not affected. Contractile activity also modified the mitochondrial content of proteins comprising the import machinery, as evident from increases in the levels of the intramitochondrial chaperone mtHSP70 as well as the outer membrane import receptor Tom20 in SS and IMF mitochondria. Addition of cytosol isolated from stimulated or control muscles to the import reaction resulted in similar twofold increases in the ability of mitochondria to import malate dehydrogenase, despite elevations in the concentration of mitochondrial import-stimulating factor within the cytosol of chronically stimulated muscle. These results suggest that chronic contractile activity modifies the extra- and intramitochondrial environments in a fashion that favors the acceleration of precursor protein import into the matrix of the organelle. This increase in protein import is likely an important adaptation in the overall process of mitochondrial biogenesis.

scholarly journals A model system for mitochondrial biogenesis reveals evolutionary rewiring of protein import and membrane assembly pathways

2012 ◽  
Vol 109 (49) ◽  
pp. E3358-E3366 ◽  
Author(s):  
V. L. Hewitt ◽  
E. Heinz ◽  
M. Shingu-Vazquez ◽  
Y. Qu ◽  
B. Jelicic ◽  
...  
Keyword(s):  
Mitochondrial Biogenesis ◽  
Protein Import ◽  
Model System ◽  
Membrane Assembly ◽  
Assembly Pathways

scholarly journals Evolution of mitochondrial protein import – lessons from trypanosomes

2020 ◽  
Vol 401 (6-7) ◽  
pp. 663-676 ◽  
Author(s):  
André Schneider
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Protein Import ◽  
Outer Membrane Proteins ◽  
Mitochondrial Protein ◽  
Intermembrane Space ◽  
Mitochondrial Protein Import ◽  
System A ◽  
Import Receptors ◽  
Inner Membrane Protein

AbstractThe evolution of mitochondrial protein import and the systems that mediate it marks the boundary between the endosymbiotic ancestor of mitochondria and a true organelle that is under the control of the nucleus. Protein import has been studied in great detail in Saccharomyces cerevisiae. More recently, it has also been extensively investigated in the parasitic protozoan Trypanosoma brucei, making it arguably the second best studied system. A comparative analysis of the protein import complexes of yeast and trypanosomes is provided. Together with data from other systems, this allows to reconstruct the ancestral features of import complexes that were present in the last eukaryotic common ancestor (LECA) and to identify which subunits were added later in evolution. How these data can be translated into plausible scenarios is discussed, providing insights into the evolution of (i) outer membrane protein import receptors, (ii) proteins involved in biogenesis of α-helically anchored outer membrane proteins, and (iii) of the intermembrane space import and assembly system. Finally, it is shown that the unusual presequence-associated import motor of trypanosomes suggests a scenario of how the two ancestral inner membrane protein translocases present in LECA evolved into the single bifunctional one found in extant trypanosomes.

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.

scholarly journals Two components of the chloroplast protein import apparatus, IAP86 and IAP75, interact with the transit sequence during the recognition and translocation of precursor proteins at the outer envelope.

1996 ◽  
Vol 134 (2) ◽  
pp. 315-327 ◽  
Author(s):  
Y Ma ◽  
A Kouranov ◽  
S E LaSala ◽  
D J Schnell
Keyword(s):  
Outer Membrane ◽  
Protein Import ◽  
Small Subunit ◽  
Chloroplast Envelope ◽  
Stable Complex ◽  
Nucleoside Triphosphate ◽  
Cross Linking ◽  
Outer Envelope ◽  
Bisphosphate Carboxylase ◽  
Precursor Proteins

The interactions of precursor proteins with components of the chloroplast envelope were investigated during the early stages of protein import using a chemical cross-linking strategy. In the absence of energy, two components of the outer envelope import machinery, IAP86 and IAP75, cross-linked to the transit sequence of the precursor to the small subunit of ribulose-1, 5-bisphosphate carboxylase (pS) in a precursor binding assay. In the presence of concentrations of ATP or GTP that support maximal precursor binding to the envelope, cross-linking to the transit sequence occurred predominantly with IAP75 and a previously unidentified 21-kD polypeptide of the inner membrane, indicating that the transit sequence had inserted across the outer membrane. Cross-linking of envelope components to sequences in the mature portion of a second precursor, preferredoxin, was detected in the presence of ATP or GTP, suggesting that sequences distant from the transit sequence were brought into the vicinity of the outer membrane under these conditions. IAP75 and a third import component, IAP34, were coimmunoprecipitated with IAP86 antibodies from solubilized envelope membranes, indicating that these three proteins form a stable complex in the outer membrane. On the basis of these observations, we propose that IAP86 and IAP75 act as components of a multisubunit complex to mediate energy-independent recognition of the transit sequence and subsequent nucleoside triphosphate-induced insertion of the transit sequence across the outer membrane.

Functional consequences of thyroid hormone-induced changes in the mitochondrial protein import pathway

2003 ◽  
Vol 284 (1) ◽  
pp. E29-E35 ◽  
Author(s):  
Marco Colavecchia ◽  
Loraine N. Christie ◽  
Yashpal S. Kanwar ◽  
David A. Hood
Keyword(s):  
Thyroid Hormone ◽  
Mitochondrial Biogenesis ◽  
Protein Import ◽  
Mitochondrial Protein ◽  
Cardiac Cells ◽  
Mrna Levels ◽  
Functional Changes ◽  
Functional Consequences ◽  
Induced Changes ◽  
In Cells

Thyroid hormone [3,5,3′-triiodo-l-thyronine (T3)] induces phenotypic alterations in cardiac mitochondria, in part by influencing protein import and the expression of the import motor mitochondrial heat shock protein (mtHsp70). Here we examined the adaptability of translocases of the inner membrane (Tim) proteins, as well as the outer membrane receptor Tom34, to T3. Administration of T3 to rats for 5 days increased cardiac Tim23 and Tim44 mRNA levels by 55 and 50%, respectively, but had no effect on Tim17. T3 treatment also induced a 45% increase in Tom34 mRNA, with no accompanying changes at the protein level, suggesting regulation at the posttranscriptional level. In H9c2 cardiac cells, Tim17 mRNA was elevated by 114% by 9 days of differentiation, whereas Tim23 and Tim44 declined by 25 and 29%, respectively. To determine the functional consequences of these T3-induced changes, malate dehydrogenase (MDH) import rates were measured in H9c2 cells stably overexpressing Tim44 and mtHsp70, either alone or in combination. MDH import remained unaltered in cells overexpressing Tim44 or in cells overexpressing both Tim44 and mtHsp70. However, when mtHsp70 was overexpressed alone, a 13% ( P < 0.05) increase in MDH import rate was observed. These findings indicate that import machinery components are differentially regulated in response to stimuli that induce mitochondrial biogenesis, like T3 and differentiation. In addition, the induction of an import machinery component in response to T3 may not necessarily result in functional changes in protein import during mitochondrial biogenesis. Finally, mtHsp70 may play a regulatory role in the import process that is independent of its interaction with Tim44.

scholarly journals The novel chloroplast outer membrane kinase KOC1 is a required component of the plastid protein import machinery

2017 ◽  
Vol 292 (17) ◽  
pp. 6952-6964 ◽  
Author(s):  
Mónica Zufferey ◽  
Cyrille Montandon ◽  
Véronique Douet ◽  
Emilie Demarsy ◽  
Birgit Agne ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Protein Import ◽  
The Novel ◽  
Plastid Protein

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.

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