1
|
Crouser ED, Julian MW, Huff JE, Mandich DV, Green-Church KB. A proteomic analysis of liver mitochondria during acute endotoxemia. Intensive Care Med 2006; 32:1252-62. [PMID: 16741687 DOI: 10.1007/s00134-006-0224-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2005] [Accepted: 05/02/2006] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Accumulating evidence indicates that mitochondrial function is impaired in vital organs during sepsis. In addition to oxidative phosphorylation, mitochondria participate in diverse cellular functions ranging from protein and lipid metabolism to programmed cell death. We analyzed liver mitochondrial protein expression patterns (i.e., proteomics) during acute endotoxemia to discover novel insights into mitochondrial responses to acute systemic inflammation. DESIGN A normotensive endotoxemia model was employed in which altered mitochondrial morphology occurs under conditions minimizing the potentially confounding effects of tissue hypoxia and acidosis. SETTING University medical research laboratory. SUBJECTS Random-source, adult, male cats. INTERVENTIONS Hemodynamic resuscitation and maintenance of acid-base balance and tissue oxygen availability were provided to preserve baseline homeostatic conditions. Treatment groups received isotonic saline vehicle (control; n = 5) or endotoxin (lipopolysaccharide, LPS, at 3.0 mg/kg intravenously; n = 5]. Liver samples were obtained 4 h posttreatment, and mitochondrial proteins were isolated and quantitatively compared using two-dimensional gel electrophoresis. Differentially expressed proteins (> 1.5-fold change relative to controls) were identified using mass spectrometry. MEASUREMENTS AND RESULTS Among over 500 protein spots that were separated 14 were differentially expressed in mitochondria of LPS-treated animals relative to matching controls. Spectrometric analyses demonstrated increased expression of urea cycle enzymes, heat shock protein (HSP) 60 and manganese superoxide dismutase, whereas expression of HSP70, F(1)-ATPase and key enzymes regulating lipid metabolism was reduced. CONCLUSIONS Considering the known functions of each of the proteins exhibiting altered expression, it is likely that the observed changes in liver mitochondrial protein expression are reflective of significant changes in mitochondrial function in response to endotoxemia.
Collapse
Affiliation(s)
- Elliott D Crouser
- Division of Pulmonary, Critical Care and Sleep Medicine, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, 473 West 12 Avenue, Columbus, OH 43210-1252, USA.
| | | | | | | | | |
Collapse
|
2
|
Mihara K, Omura T. Cytoplasmic chaperones in precursor targeting to mitochondria: the role of MSF and hsp 70. Trends Cell Biol 2005; 6:104-8. [PMID: 15157486 DOI: 10.1016/0962-8924(96)81000-2] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Despite extensive study since the early 1980s, the mechanism by which newly synthesized protein precursors are unfolded in the cytoplasm and targeted correctly to the mitochondrial surface prior to translocation through the mitochondrial membranes is understood poorly. Recently, an N-ethylmaleimide (NEM)-sensitive cytoplasmic factor called mitochondrial import stimulation factor (MSF), which catalyses the ATP-dependent unfolding of precursor proteins, was described. Unlike the more general chaperone proteins of the hsp70 families, MSF not only unfolds proteins but also targets the unfolded precursor proteins to the mitochondria. Here, Mihara and Omura summarize what is known about MSF and speculate on how it, and other cytoplasmic factors, may be involved in mitochondrial import.
Collapse
Affiliation(s)
- K Mihara
- Dept of Molecular Biology, Graduate School of Medical Science, Fukuoka 812, Japan
| | | |
Collapse
|
3
|
Yano M, Hoogenraad N, Terada K, Mori M. Identification and functional analysis of human Tom22 for protein import into mitochondria. Mol Cell Biol 2000; 20:7205-13. [PMID: 10982837 PMCID: PMC86274 DOI: 10.1128/mcb.20.19.7205-7213.2000] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mitochondria have a receptor complex in the outer membrane which recognizes and translocates mitochondrial proteins synthesized in the cytosol. We report here the identification and functional analysis of human Tom22 (hTom22). hTom22 has an N-terminal negatively charged region exposed to the cytosol, a putative transmembrane region, and a C-terminal intermembrane space region with little negative charge. Tom22 forms a complex with Tom20, and its cytosolic domain functions as an import receptor as in fungi. An import inhibition assay, using pre-ornithine transcarbamylase (pOTC) derivatives and a series of hTom22 deletion mutants, showed that the C-terminal segment of the cytosolic domain is important for presequence binding, whereas the N-terminal domain is important for binding to the mature portion of pOTC. No evidence for pOTC interaction with the Tom22 intermembrane space domain was obtained. Binding studies revealed that the presequence is critical for pOTC binding to Tom20, whereas both the presequence and mature portion are important for binding to Tom22. A cell-free immunoprecipitation assay indicated that an internal segment of the Tom22 cytosolic domain is important for interaction with Tom20.
Collapse
Affiliation(s)
- M Yano
- Department of Molecular Genetics, Kumamoto University School of Medicine, Kumamoto 860-0811, Japan
| | | | | | | |
Collapse
|
4
|
Abstract
A clear picture has emerged over the past years on how a 'classic' mitochondrial protein, like subunit IV of cytochrome c oxidase, might be targeted to mitochondria. The targeting and subsequent import process involves the commitment of the TOM (translocase in the outer mitochondrial membrane) receptor complex on the mitochondrial surface, a TIM (translocase in the inner mitochondrial membrane) translocation complex in the mitochondrial inner membrane, and assorted chaperones and processing enzymes within the organelle. Recent work suggests that while very many mitochondrial precursor proteins might follow this basic targeting pathway, a large number have further requirements if they are to be successfully imported. These include ribosome-associated factors and soluble factors in the cytosol, soluble factors in the mitochondrial intermembrane space, an additional TIM translocase in the inner membrane and a range of narrow specificity assembly factors in the inner membrane. This review is focused on the targeting of proteins up to the stage at which they enter the TOM complex in the outer membrane.
Collapse
Affiliation(s)
- T Lithgow
- Russell Grimwade School of Biochemistry and Molecular Biology, University of Melbourne, Vic. 3010, Parkville, Australia.
| |
Collapse
|
5
|
Seibel M, Bachmann C, Schmiedel J, Wilken N, Wilde F, Reichmann H, Isaya G, Seibel P, Pfeiler D. Processing of artificial peptide-DNA-conjugates by the mitochondrial intermediate peptidase (MIP). Biol Chem 1999; 380:961-7. [PMID: 10494848 DOI: 10.1515/bc.1999.119] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Import of DNA from the cytoplasm into the mitochondrial matrix is an obligatory step for an in organello site-directed mutagenesis or gene therapy approach on mitochondrial DNA diseases. In this context, we have developed an artificial DNA translocation vector that is composed of the mitochondrial signal peptide of the ornithine transcarbamylase (OTC) and a DNA moiety. While this vector is capable of directing attached passenger molecules to the mitochondrial matrix, the recognition of this artificial molecule by the endogenous mitochondrial signal peptide processing machinery as well as the cleavage of the peptide plays a pivotal role in the release of the attached DNA. To study the proteolytic processing of the artificial vector, various signal peptide-DNA-conjugates were treated with purified mitochondrial intermediate peptidase. When the leader peptide is directly linked to the DNA moiety without an intervening spacer, MIP processing is prevented. Cleavage of the peptide can be restored, however, when the first ten amino acid residues of the mature part of OTC are appended at the carboxy-terminal end of the signal peptide. Our results show that artificial peptide-DNA-conjugates are recognized by the mitochondrial proteolytic machinery, and therefore an interference of the peptide with the DNA function can be excluded.
Collapse
Affiliation(s)
- M Seibel
- Forschungsgruppe Neurobiochemie und Zellbiologie, Neurologische Klinik und Poliklinik, Dresden, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Affiliation(s)
- M Mori
- Department of Molecular Genetics, Kumamoto University School of Medicine, Kuhonji 4-24-1, Kumamoto 862, Japan.
| | | |
Collapse
|
7
|
Ryan MT, Naylor DJ, Høj PB, Clark MS, Hoogenraad NJ. The role of molecular chaperones in mitochondrial protein import and folding. INTERNATIONAL REVIEW OF CYTOLOGY 1997; 174:127-93. [PMID: 9161007 DOI: 10.1016/s0074-7696(08)62117-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Molecular chaperones play a critical role in many cellular processes. This review concentrates on their role in targeting of proteins to the mitochondria and the subsequent folding of the imported protein. It also reviews the role of molecular chaperons in protein degradation, a process that not only regulates the turnover of proteins but also eliminates proteins that have folded incorrectly or have aggregated as a result of cell stress. Finally, the role of molecular chaperones, in particular to mitochondrial chaperonins, in disease is reviewed. In support of the endosymbiont theory on the origin of mitochondria, the chaperones of the mitochondrial compartment show a high degree of similarity to bacterial molecular chaperones. Thus, studies of protein folding in bacteria such as Escherichia coli have proved to be instructive in understanding the process in the eukaryotic cell. As in bacteria, the molecular chaperone genes of eukaryotes are activated by a variety of stresses. The regulation of stress genes involved in mitochondrial chaperone function is reviewed and major unsolved questions regarding the regulation, function, and involvement in disease of the molecular chaperones are identified.
Collapse
Affiliation(s)
- M T Ryan
- School of Biochemistry, La Trobe University, Bundoora, Victoria, Australia
| | | | | | | | | |
Collapse
|
8
|
Abstract
In vitro import studies have confirmed the participation of cytosolic protein factors in the import of various precursor proteins into mitochondria. The requirement for extramitochondrial adenosine triphosphate for the import of a group of precursor proteins seems to be correlated with the chaperone activity of the cytosolic protein factors. One of the cytosolic protein factors is hsp70, which generally recognizes and binds unfolded proteins in the cytoplasm. Hsp70 keeps the newly synthesized mitochondrial precursor proteins in import-competent unfolded conformations. Another cytosolic protein factor that has been characterized is mitochondrial import stimulation factor (MSF), which seems to be specific to mitochondrial precursor proteins. MSF recognizes the mitochondrial precursor proteins, forms a complex with them and targets them to the receptors on the outer surface of mitochondria.
Collapse
Affiliation(s)
- K Mihara
- Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, Fukuoka, Japan.
| | | |
Collapse
|
9
|
Robinson KM, Lemire BD. A requirement for matrix processing peptidase but not for mitochondrial chaperonin in the covalent attachment of FAD to the yeast succinate dehydrogenase flavoprotein. J Biol Chem 1996; 271:4061-7. [PMID: 8626740 DOI: 10.1074/jbc.271.8.4061] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Succinate dehydrogenase (EC 1.3.99.1) in the yeast Saccharomyces cerevisiae is a mitochondrial heterotetramer containing a flavoprotein subunit with an 8alpha-N(3)-histidyl-linked FAD cofactor. The covalent linkage of the FAD is necessary for activity. We have developed an in vitro assay that measures the flavinylation of the flavoprotein precursor in mitochondrial matrix fractions. Flavoprotein modification does not depend on translocation across a membrane, but it does require proteolytic processing by the mitochondrial processing peptidase prior to flavin attachment. Since ATP depletion, N-ethylmaleimide, or proteinase treatments of matrix fractions inhibit flavoprotein modification, at least one additional matrix protein component appears to be required. Having previously suggested that the flavoprotein begins folding before FAD attachment occurs, we tested whether the mitochondrial chaperonin, heat shock protein 60, might be necessary. Co-immunoprecipitation of the flavoprotein and the chaperonin demonstrate that the proteins do indeed interact. However, immunodepletion of the chaperonin from matrix fractions does not inhibit FAD attachment. Nonprotein components are also required for flavoprotein modification. In addition to ATP, effector molecules such as succinate, fumarate, or malate also stimulate modification. Together, these results suggest that FAD addition is an early event in succinate dehydrogenase assembly.
Collapse
Affiliation(s)
- K M Robinson
- Medical Research Council of Canada Group in the Molecular Biology of Membranes, Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | | |
Collapse
|
10
|
Affiliation(s)
- K Mihara
- Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, Fukuoka, Japan
| | | |
Collapse
|
11
|
Refolding of the precursor and mature forms of mitochondrial aspartate aminotransferase after guanidine hydrochloride denaturation. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)41526-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
|
12
|
Lathrop JT, Timko MP. Regulation by heme of mitochondrial protein transport through a conserved amino acid motif. Science 1993; 259:522-5. [PMID: 8424176 DOI: 10.1126/science.8424176] [Citation(s) in RCA: 220] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A conserved motif, termed the heme regulatory motif (HRM), was identified in the presequences of the erythroid delta-aminolevulinate synthase precursors and was shown to be involved in hemin inhibition of transport of these proteins into mouse mitochondria in vitro. When the HRM was inserted into the presequence of the ornithine transcarbamoylase precursor, a normally unregulated mitochondrial protein, it conferred hemin inhibition on the transport of the chimeric protein. The conserved cysteine within the HRM was shown by site-directed mutagenesis to be required for hemin inhibition.
Collapse
Affiliation(s)
- J T Lathrop
- Department of Biology, University of Virginia, Charlottesville 22901
| | | |
Collapse
|
13
|
Murakami K, Tanase S, Morino Y, Mori M. Presequence binding factor-dependent and -independent import of proteins into mitochondria. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42177-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
14
|
Targeting of a chemically pure preprotein to mitochondria does not require the addition of a cytosolic signal recognition factor. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42813-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
|
15
|
Jeng JJ, Weiner H. Purification and characterization of catalytically active precursor of rat liver mitochondrial aldehyde dehydrogenase expressed in Escherichia coli. Arch Biochem Biophys 1991; 289:214-22. [PMID: 1898068 DOI: 10.1016/0003-9861(91)90464-t] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The cDNA coding for the precursor (p-ALDH) or mature (m-ALDH) rat liver mitochondrial aldehyde dehydrogenase was cloned in an expression vector pT7-7 and expressed in Escherichia coli strain BL21 (DE3)/plysS. The p-ALDH expressed in E. coli was a soluble tetrameric protein. It exhibited virtually the same specific activity and KmS for substrates as m-ALDH. N-terminal sequencing of isolated p-ALDH provided the evidence that the catalytic activity was not derived from a partially processed mature-like enzyme. The assembly states of both p-ALDH and m-ALDH synthesized in a rabbit reticulocyte lysate were also determined. Both of them were monomers and could not bind to a 5'-AMP-Sepharose column, showing that the monomeric form of the enzyme is inactive. The stabilities in vivo and in vitro were compared between p-ALDH and m-ALDH expressed in E. coli. p-ALDH was less stable than was m-ALDH both in vivo and in vitro. Thus, although the conformations of p-ALDH and m-ALDH are similar, the presence of signal peptide is a destabilizing factor to the p-ALDH. p-ALDH expressed in E. coli could bind to and be translocated into rat liver mitochondria, however, with lower efficiency when compared to the import of p-ALDH synthesized in reticulocyte lysate.
Collapse
Affiliation(s)
- J J Jeng
- Departmen of Biochemistry, Purdue University, West Lafayette, Indiana 47907
| | | |
Collapse
|
16
|
Krieg UC, Scherer PE. Purified precursor proteins for studying protein import into yeast mitochondria. Methods Cell Biol 1991; 34:409-18. [PMID: 1943815 DOI: 10.1016/s0091-679x(08)61695-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- U C Krieg
- Department of Biochemistry, University of Basel, Switzerland
| | | |
Collapse
|
17
|
Horwich AL, Cheng M, West A, Pollock RA. Mitochondrial protein import. Curr Top Microbiol Immunol 1991; 170:1-42. [PMID: 1760928 DOI: 10.1007/978-3-642-76389-2_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A dynamic picture of the mitochondrial protein import pathway is emerging, with conformational alteration a critical feature both preceding and following membrane translocation. The mediators of these steps of conformational alteration, as well as steps of recognition, translocation, and proteolytic cleavage, appear to be proteins. Using powerful tools of genetics and biochemistry, in years to come it should be possible to determine the precise molecular function of these proteins in mediating these novel reactions.
Collapse
Affiliation(s)
- A L Horwich
- Department of Human Genetics, Yale University, School of Medicine, New Haven, CT 06510-8005
| | | | | | | |
Collapse
|
18
|
Pilon M, de Boer AD, Knols SL, Koppelman MH, van der Graaf RM, de Kruijff B, Weisbeek PJ. Expression in Escherichia coli and purification of a translocation-competent precursor of the chloroplast protein ferredoxin. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)39775-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
19
|
Ubiquitin is Involved in the in vitro Insertion of Monoamine Oxidase B into Mitochondrial Outer Membranes. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)63734-2] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
|