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Sazanov LA. From the 'black box' to 'domino effect' mechanism: what have we learned from the structures of respiratory complex I. Biochem J 2023; 480:319-333. [PMID: 36920092 DOI: 10.1042/bcj20210285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Revised: 01/20/2023] [Accepted: 01/23/2023] [Indexed: 03/16/2023]
Abstract
My group and myself have studied respiratory complex I for almost 30 years, starting in 1994 when it was known as a L-shaped giant 'black box' of bioenergetics. First breakthrough was the X-ray structure of the peripheral arm, followed by structures of the membrane arm and finally the entire complex from Thermus thermophilus. The developments in cryo-EM technology allowed us to solve the first complete structure of the twice larger, ∼1 MDa mammalian enzyme in 2016. However, the mechanism coupling, over large distances, the transfer of two electrons to pumping of four protons across the membrane remained an enigma. Recently we have solved high-resolution structures of mammalian and bacterial complex I under a range of redox conditions, including catalytic turnover. This allowed us to propose a robust and universal mechanism for complex I and related protein families. Redox reactions initially drive conformational changes around the quinone cavity and a long-distance transfer of substrate protons. These set up a stage for a series of electrostatically driven proton transfers along the membrane arm ('domino effect'), eventually resulting in proton expulsion from the distal antiporter-like subunit. The mechanism radically differs from previous suggestions, however, it naturally explains all the unusual structural features of complex I. In this review I discuss the state of knowledge on complex I, including the current most controversial issues.
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Affiliation(s)
- Leonid A Sazanov
- Institute of Science and Technology Austria, Am Campus 1, Klosterneuburg 3400, Austria
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2
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Sordaria macrospora Sterile Mutant pro34 Is Impaired in Respiratory Complex I Assembly. J Fungi (Basel) 2022; 8:jof8101015. [PMID: 36294581 PMCID: PMC9605262 DOI: 10.3390/jof8101015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 09/22/2022] [Accepted: 09/23/2022] [Indexed: 11/21/2022] Open
Abstract
The formation of fruiting bodies is a highly regulated process that requires the coordinated formation of different cell types. By analyzing developmental mutants, many developmental factors have already been identified. Yet, a complete understanding of fruiting body formation is still lacking. In this study, we analyzed developmental mutant pro34 of the filamentous ascomycete Sordaria macrospora. Genome sequencing revealed a deletion in the pro34 gene encoding a putative mitochondrial complex I assembly factor homologous to Neurospora crassa CIA84. We show that PRO34 is required for fast vegetative growth, fruiting body and ascospore formation. The pro34 transcript undergoes adenosine to inosine editing, a process correlated with sexual development in fruiting body-forming ascomycetes. Fluorescence microscopy and western blot analysis showed that PRO34 is a mitochondrial protein, and blue-native PAGE revealed that the pro34 mutant lacks mitochondrial complex I. Inhibitor experiments revealed that pro34 respires via complexes III and IV, but also shows induction of alternative oxidase, a shunt pathway to bypass complexes III and IV. We discuss the hypothesis that alternative oxidase is induced to prevent retrograde electron transport to complex I intermediates, thereby protecting from oxidative stress.
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3
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Tsviklist V, Guest RL, Raivio TL. The Cpx Stress Response Regulates Turnover of Respiratory Chain Proteins at the Inner Membrane of Escherichia coli. Front Microbiol 2022; 12:732288. [PMID: 35154019 PMCID: PMC8831704 DOI: 10.3389/fmicb.2021.732288] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 12/20/2021] [Indexed: 12/03/2022] Open
Abstract
The Cpx envelope stress response is a major signaling pathway monitoring bacterial envelope integrity, activated both internally by excessive synthesis of membrane proteins and externally by a variety of environmental cues. The Cpx regulon is enriched with genes coding for protein folding and degrading factors, virulence determinants, and large envelope-localized complexes. Transcriptional repression of the two electron transport chain complexes, NADH dehydrogenase I and cytochrome bo3, by the Cpx pathway has been demonstrated, however, there is evidence that additional regulatory mechanisms exist. In this study, we examine the interaction between Cpx-regulated protein folding and degrading factors and the respiratory complexes NADH dehydrogenase I and succinate dehydrogenase in Escherichia coli. Here we show that the cellular need for Cpx-mediated stress adaptation increases when respiratory complexes are more prevalent or active, which is demonstrated by the growth defect of Cpx-deficient strains on media that requires a functional electron transport chain. Interestingly, deletion of several Cpx-regulated proteolytic factors and chaperones results in similar growth-deficient phenotypes. Furthermore, we find that the stability of the NADH dehydrogenase I protein complex is lower in cells with a functional Cpx response, while in its absence, protein turnover is impaired. Finally, we demonstrated that the succinate dehydrogenase complex has reduced activity in E. coli lacking the Cpx pathway. Our results suggest that the Cpx two-component system serves as a sentry of inner membrane protein biogenesis, ensuring the function of large envelope protein complexes and maintaining the cellular energy status of the cell.
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Affiliation(s)
- Valeria Tsviklist
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Randi L. Guest
- Lewis Thomas Laboratory, Department of Molecular Biology, Princeton University, Princeton, NJ, United States
| | - Tracy L. Raivio
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
- *Correspondence: Tracy L. Raivio,
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4
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Mitochondrial iron-sulfur clusters: Structure, function, and an emerging role in vascular biology. Redox Biol 2021; 47:102164. [PMID: 34656823 PMCID: PMC8577454 DOI: 10.1016/j.redox.2021.102164] [Citation(s) in RCA: 88] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/04/2021] [Accepted: 10/08/2021] [Indexed: 12/31/2022] Open
Abstract
Iron-sulfur (Fe-S) clusters are essential cofactors most commonly known for their role mediating electron transfer within the mitochondrial respiratory chain. The Fe-S cluster pathways that function within the respiratory complexes are highly conserved between bacteria and the mitochondria of eukaryotic cells. Within the electron transport chain, Fe-S clusters play a critical role in transporting electrons through Complexes I, II and III to cytochrome c, before subsequent transfer to molecular oxygen. Fe-S clusters are also among the binding sites of classical mitochondrial inhibitors, such as rotenone, and play an important role in the production of mitochondrial reactive oxygen species (ROS). Mitochondrial Fe-S clusters also play a critical role in the pathogenesis of disease. High levels of ROS produced at these sites can cause cell injury or death, however, when produced at low levels can serve as signaling molecules. For example, Ndufs2, a Complex I subunit containing an Fe-S center, N2, has recently been identified as a redox-sensitive oxygen sensor, mediating homeostatic oxygen-sensing in the pulmonary vasculature and carotid body. Fe-S clusters are emerging as transcriptionally-regulated mediators in disease and play a crucial role in normal physiology, offering potential new therapeutic targets for diseases including malaria, diabetes, and cancer.
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5
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The road to the structure of the mitochondrial respiratory chain supercomplex. Biochem Soc Trans 2021; 48:621-629. [PMID: 32311046 PMCID: PMC7200630 DOI: 10.1042/bst20190930] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 03/30/2020] [Accepted: 03/31/2020] [Indexed: 01/04/2023]
Abstract
The four complexes of the mitochondrial respiratory chain are critical for ATP production in most eukaryotic cells. Structural characterisation of these complexes has been critical for understanding the mechanisms underpinning their function. The three proton-pumping complexes, Complexes I, III and IV associate to form stable supercomplexes or respirasomes, the most abundant form containing 80 subunits in mammals. Multiple functions have been proposed for the supercomplexes, including enhancing the diffusion of electron carriers, providing stability for the complexes and protection against reactive oxygen species. Although high-resolution structures for Complexes III and IV were determined by X-ray crystallography in the 1990s, the size of Complex I and the supercomplexes necessitated advances in sample preparation and the development of cryo-electron microscopy techniques. We now enjoy structures for these beautiful complexes isolated from multiple organisms and in multiple states and together they provide important insights into respiratory chain function and the role of the supercomplex. While we as non-structural biologists use these structures for interpreting our own functional data, we need to remind ourselves that they stand on the shoulders of a large body of previous structural studies, many of which are still appropriate for use in understanding our results. In this mini-review, we discuss the history of respiratory chain structural biology studies leading to the structures of the mammalian supercomplexes and beyond.
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6
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Song WS, Shin SG, Jo SH, Lee JS, Jeon HJ, Kwon JE, Park JH, Cho S, Jeong JH, Kim BG, Kim YG. Development of an in vitro coculture device for the investigation of host-microbe interactions via integrative multiomics approaches. Biotechnol Bioeng 2021; 118:1612-1623. [PMID: 33421096 DOI: 10.1002/bit.27676] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 12/26/2020] [Accepted: 12/29/2020] [Indexed: 01/05/2023]
Abstract
The commensal gut bacterium Akkermansia muciniphila is well known as a promising probiotic candidate that improves host health and prevents diseases. However, the biological interaction of A. muciniphila with human gut epithelial cells has rarely been explored for use in biotherapeutics. Here, we developed an in vitro device that simulates the gut epithelium to elucidate the biological effects of living A. muciniphila via multiomics analysis: the Mimetic Intestinal Host-Microbe Interaction Coculture System (MIMICS). We demonstrated that both human intestinal epithelial cells (Caco-2) and the anaerobic bacterium A. muciniphila can remain viable for 12 h after coculture in the MIMICS. The transcriptomic and proteomic changes (cell-cell junctions, immune responses, and mucin secretion) in gut epithelial cells treated with A. muciniphila closely correspond with those reported in previous in vivo studies. In addition, our proteomic and metabolomic results revealed that A. muciniphila activates glucose and lipid metabolism in gut epithelial cells, leading to an increase in ATP production. This study suggests that A. muciniphila improves metabolism for ATP production in gut epithelial cells and that the MIMICS may be an effective general tool for evaluating the effects of anaerobic bacteria on gut epithelial cells.
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Affiliation(s)
- Won-Suk Song
- School of Chemical and Biological Engineering, Seoul National University, Seoul, Korea
| | - Sung Gyu Shin
- Department of Chemical Engineering, Soongsil University, Seoul, Korea
| | - Sung-Hyun Jo
- Department of Chemical Engineering, Soongsil University, Seoul, Korea
| | - Jae-Seung Lee
- Department of Chemical Engineering, Soongsil University, Seoul, Korea
| | - Hyo-Jin Jeon
- Department of Chemical Engineering, Soongsil University, Seoul, Korea
| | - Ji-Eun Kwon
- Department of Chemical Engineering, Soongsil University, Seoul, Korea
| | - Ji-Hyeon Park
- Department of Chemical Engineering, Soongsil University, Seoul, Korea
| | - Sungwoo Cho
- Department of Chemical Engineering, Soongsil University, Seoul, Korea
| | - Jae Hyun Jeong
- Department of Chemical Engineering, Soongsil University, Seoul, Korea
| | - Byung-Gee Kim
- School of Chemical and Biological Engineering, Seoul National University, Seoul, Korea
| | - Yun-Gon Kim
- Department of Chemical Engineering, Soongsil University, Seoul, Korea
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7
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Wu M, Gu J, Zong S, Guo R, Liu T, Yang M. Research journey of respirasome. Protein Cell 2020; 11:318-338. [PMID: 31919741 PMCID: PMC7196574 DOI: 10.1007/s13238-019-00681-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Accepted: 12/11/2019] [Indexed: 12/11/2022] Open
Abstract
Respirasome, as a vital part of the oxidative phosphorylation system, undertakes the task of transferring electrons from the electron donors to oxygen and produces a proton concentration gradient across the inner mitochondrial membrane through the coupled translocation of protons. Copious research has been carried out on this lynchpin of respiration. From the discovery of individual respiratory complexes to the report of the high-resolution structure of mammalian respiratory supercomplex I1III2IV1, scientists have gradually uncovered the mysterious veil of the electron transport chain (ETC). With the discovery of the mammalian respiratory mega complex I2III2IV2, a new perspective emerges in the research field of the ETC. Behind these advances glitters the light of the revolution in both theory and technology. Here, we give a short review about how scientists 'see' the structure and the mechanism of respirasome from the macroscopic scale to the atomic scale during the past decades.
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Affiliation(s)
- Meng Wu
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Jinke Gu
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Shuai Zong
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Runyu Guo
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Tianya Liu
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Maojun Yang
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
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8
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The Oncojanus Paradigm of Respiratory Complex I. Genes (Basel) 2018; 9:genes9050243. [PMID: 29735924 PMCID: PMC5977183 DOI: 10.3390/genes9050243] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 04/09/2018] [Accepted: 05/03/2018] [Indexed: 02/07/2023] Open
Abstract
Mitochondrial respiratory function is now recognized as a pivotal player in all the aspects of cancer biology, from tumorigenesis to aggressiveness and chemotherapy resistance. Among the enzymes that compose the respiratory chain, by contributing to energy production, redox equilibrium and oxidative stress, complex I assumes a central role. Complex I defects may arise from mutations in mitochondrial or nuclear DNA, in both structural genes or assembly factors, from alteration of the expression levels of its subunits, or from drug exposure. Since cancer cells have a high-energy demand and require macromolecules for proliferation, it is not surprising that severe complex I defects, caused either by mutations or treatment with specific inhibitors, prevent tumor progression, while contributing to resistance to certain chemotherapeutic agents. On the other hand, enhanced oxidative stress due to mild complex I dysfunction drives an opposite phenotype, as it stimulates cancer cell proliferation and invasiveness. We here review the current knowledge on the contribution of respiratory complex I to cancer biology, highlighting the double-edged role of this metabolic enzyme in tumor progression, metastasis formation, and response to chemotherapy.
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9
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A Bacterial Stress Response Regulates Respiratory Protein Complexes To Control Envelope Stress Adaptation. J Bacteriol 2017; 199:JB.00153-17. [PMID: 28760851 DOI: 10.1128/jb.00153-17] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 07/18/2017] [Indexed: 01/02/2023] Open
Abstract
The Cpx envelope stress response mediates adaptation to stresses that affect protein folding within the envelope of Gram-negative bacteria. Recent transcriptome analyses revealed that the Cpx response impacts genes that affect multiple cellular functions predominantly associated with the cytoplasmic membrane. In this study, we examined the connection between the Cpx response and the respiratory complexes NADH dehydrogenase I and cytochrome bo3 in enteropathogenic Escherichia coli We found that the Cpx response directly represses the transcription of the nuo and cyo operons and that Cpx-mediated repression of these complexes confers adaptation to stresses that compromise envelope integrity. Furthermore, we found that the activity of the aerobic electron transport chain is reduced in E. coli lacking a functional Cpx response despite no change in the transcription of either the nuo or the cyo operon. Finally, we show that expression of NADH dehydrogenase I and cytochrome bo3 contributes to basal Cpx pathway activity and that overproduction of individual subunits can influence pathway activation. Our results demonstrate that the Cpx response gauges and adjusts the expression, and possibly the function, of inner membrane protein complexes to enable adaptation to envelope stress.IMPORTANCE Bacterial stress responses allow microbes to survive environmental transitions and conditions, such as those encountered during infection and colonization, that would otherwise kill them. Enteric microbes that inhabit or infect the gut are exposed to a plethora of stresses, including changes in pH, nutrient composition, and the presence of other bacteria and toxic compounds. Bacteria detect and adapt to many of these conditions by using envelope stress responses that measure the presence of stressors in the outermost compartment of the bacterium by monitoring its physiology. The Cpx envelope stress response plays a role in antibiotic resistance and host colonization, and we have shown that it regulates many functions at the bacterial inner membrane. In this report, we describe a novel role for the Cpx response in sensing and controlling the expression of large, multiprotein respiratory complexes at the cytoplasmic membrane of Escherichia coli The significance of our research is that it will increase our understanding of how these stress responses are involved in antibiotic resistance and the mechanisms used by bacteria to colonize the gut.
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10
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Senkler J, Senkler M, Braun HP. Structure and function of complex I in animals and plants - a comparative view. PHYSIOLOGIA PLANTARUM 2017; 161:6-15. [PMID: 28261805 DOI: 10.1111/ppl.12561] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 02/03/2017] [Accepted: 02/06/2017] [Indexed: 06/06/2023]
Abstract
The mitochondrial NADH dehydrogenase complex (complex I) has a molecular mass of about 1000 kDa and includes 40-50 subunits in animals, fungi and plants. It is composed of a membrane arm and a peripheral arm and has a conserved L-like shape in all species investigated. However, in plants and possibly some protists it has a second peripheral domain which is attached to the membrane arm on its matrix exposed side at a central position. The extra domain includes proteins resembling prokaryotic gamma-type carbonic anhydrases. We here present a detailed comparison of complex I from mammals and flowering plants. Forty homologous subunits are present in complex I of both groups of species. In addition, five subunits are present in mammalian complex I, which are absent in plants, and eight to nine subunits are present in plant complex I which do not occur in mammals. Based on the atomic structure of mammalian complex I and biochemical insights into complex I architecture from plants we mapped the species-specific subunits. Interestingly, four of the five animal-specific and five of the eight to nine plant-specific subunits are localized at the inner surface of the membrane arm of complex I in close proximity. We propose that the inner surface of the membrane arm represents a workbench for attaching proteins to complex I, which are not directly related to respiratory electron transport, like nucleoside kinases, acyl-carrier proteins or carbonic anhydrases. We speculate that further enzyme activities might be bound to this micro-location in other groups of organisms.
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Affiliation(s)
- Jennifer Senkler
- Institut für Pflanzengenetik, Leibniz Universität Hannover, Hannover, 30419, Germany
| | - Michael Senkler
- Institut für Pflanzengenetik, Leibniz Universität Hannover, Hannover, 30419, Germany
| | - Hans-Peter Braun
- Institut für Pflanzengenetik, Leibniz Universität Hannover, Hannover, 30419, Germany
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11
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The Assembly Pathway of Mitochondrial Respiratory Chain Complex I. Cell Metab 2017; 25:128-139. [PMID: 27720676 DOI: 10.1016/j.cmet.2016.09.002] [Citation(s) in RCA: 278] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 07/21/2016] [Accepted: 09/10/2016] [Indexed: 11/20/2022]
Abstract
Mitochondrial complex I is the largest integral membrane enzyme of the respiratory chain and consists of 44 different subunits encoded in the mitochondrial and nuclear genome. Its biosynthesis is a highly complicated and multifaceted process involving at least 14 additional assembly factors. How these subunits assemble into a functional complex I and where the assembly factors come into play is largely unknown. Here, we applied a dynamic complexome profiling approach to elucidate the assembly of human mitochondrial complex I and its further incorporation into respiratory chain supercomplexes. We delineate the stepwise incorporation of all but one subunit into a series of distinct assembly intermediates and their association with known and putative assembly factors, which had not been implicated in this process before. The resulting detailed and comprehensive model of complex I assembly is fully consistent with recent structural data and the remarkable modular architecture of this multiprotein complex.
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12
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Fromm S, Senkler J, Zabaleta E, Peterhänsel C, Braun HP. The carbonic anhydrase domain of plant mitochondrial complex I. PHYSIOLOGIA PLANTARUM 2016; 157:289-296. [PMID: 26829901 DOI: 10.1111/ppl.12424] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 11/06/2015] [Accepted: 12/15/2015] [Indexed: 06/05/2023]
Abstract
The mitochondrial NADH dehydrogenase complex (complex I) consists of several functional domains which independently arose during evolution. In higher plants, it contains an additional domain which includes proteins resembling gamma-type carbonic anhydrases. The Arabidopsis genome codes for five complex I-integrated gamma-type carbonic anhydrases (γCA1, γCA2, γCA3, γCAL1, γCAL2), but only three copies of this group of proteins form an individual extra domain. Biochemical analyses revealed that the domain is composed of one copy of either γCAL1 or γCAL2 plus two copies of the γCA1/γCA2 proteins. Thus, the carbonic anhydrase domain can have six distinct subunit configurations. Single and double mutants with respect to the γCA/γCAL proteins were employed to genetically dissect the function of the domain. New insights into complex I biology in plants will be reviewed and discussed.
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Affiliation(s)
- Steffanie Fromm
- Institut für Pflanzengenetik, Leibniz Universität Hannover, Hannover, 30419, Germany
- Institut für Botanik, Leibniz Universität Hannover, Hannover, 30419, Germany
| | - Jennifer Senkler
- Institut für Pflanzengenetik, Leibniz Universität Hannover, Hannover, 30419, Germany
| | - Eduardo Zabaleta
- Instituto de Investigaciones Biológicas IIB, CONICET, National University of Mar del Plata, Mar del Plata, 7600, Argentina
| | | | - Hans-Peter Braun
- Institut für Pflanzengenetik, Leibniz Universität Hannover, Hannover, 30419, Germany
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Candas D, Qin L, Fan M, Li JJ. Experimental Approaches to Study Mitochondrial Localization and Function of a Nuclear Cell Cycle Kinase, Cdk1. J Vis Exp 2016:53417. [PMID: 26967001 DOI: 10.3791/53417] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Although mitochondria possess their own transcriptional machinery, merely 1% of mitochondrial proteins are synthesized inside the organelle. The nuclear-encoded proteins are transported into mitochondria guided by their mitochondria targeting sequences (MTS); however, a majority of mitochondrial localized proteins lack an identifiable MTS. Nevertheless, the fact that MTS can instruct proteins to go into the mitochondria provides a valuable tool for studying mitochondrial functions of normally nuclear and/or cytoplasmic proteins. We have recently identified the cell cycle kinase CyclinB1/Cdk1 complex in the mitochondria. To specifically study the mitochondrial functions of this complex, mitochondrial overexpression and knock-down of this complex without interfering with its nuclear or cytoplasmic functions were essential. By tagging CyclinB1/Cdk1 with MTS, we were able to achieve mitochondrial overexpression of this complex to study its mitochondrial targets as well as functions. Via tagging dominant-negative Cdk1 with MTS, inhibition of Cdk1 activity was accomplished particularly in the mitochondria. Potential mitochondrial targets of CyclinB1/Cdk1 complex were identified using a gel-based proteomics approach. Unlike traditional 2D gel analysis, we employed 2-dimensional difference gel electrophoresis (2D-DIGE) technology followed by phosphoprotein staining to fluorescently label differentially phosphorylated proteins in mitochondrial Cdk1 expressing cells. Identification of phosphoprotein spots that were altered in wild type versus dominant negative Cdk1 bearing mitochondria revealed the identity of mitochondrial targets of Cdk1. Finally, to determine the effect of CyclinB1/Cdk1 mitochondrial localization in cell cycle progression, a cell proliferation assay using a synthetic thymidine analogue EdU (5-ethynyl-2'-deoxyuridine) was used to monitor the cells as they go through the cell cycle and replicate their DNA. Altogether, we demonstrated a variety of approaches available to study mitochondrial localization and activity of a cell cycle kinase. These are advanced, yet easy to follow methods that will be beneficial to many cell biology researchers.
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Affiliation(s)
- Demet Candas
- Radiation Oncology, University of California, Davis;
| | - Lili Qin
- Radiation Oncology, University of California, Davis
| | - Ming Fan
- Radiation Oncology, University of California, Davis
| | - Jian-Jian Li
- Radiation Oncology, University of California, Davis
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14
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Wirth C, Brandt U, Hunte C, Zickermann V. Structure and function of mitochondrial complex I. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:902-14. [PMID: 26921811 DOI: 10.1016/j.bbabio.2016.02.013] [Citation(s) in RCA: 215] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 02/16/2016] [Accepted: 02/17/2016] [Indexed: 12/13/2022]
Abstract
Proton-pumping NADH:ubiquinone oxidoreductase (complex I) is the largest and most complicated enzyme of the respiratory chain. Fourteen central subunits represent the minimal form of complex I and can be assigned to functional modules for NADH oxidation, ubiquinone reduction, and proton pumping. In addition, the mitochondrial enzyme comprises some 30 accessory subunits surrounding the central subunits that are not directly associated with energy conservation. Complex I is known to release deleterious oxygen radicals (ROS) and its dysfunction has been linked to a number of hereditary and degenerative diseases. We here review recent progress in structure determination, and in understanding the role of accessory subunits and functional analysis of mitochondrial complex I. For the central subunits, structures provide insight into the arrangement of functional modules including the substrate binding sites, redox-centers and putative proton channels and pump sites. Only for two of the accessory subunits, detailed structures are available. Nevertheless, many of them could be localized in the overall structure of complex I, but most of these assignments have to be considered tentative. Strikingly, redox reactions and proton pumping machinery are spatially completely separated and the site of reduction for the hydrophobic substrate ubiquinone is found deeply buried in the hydrophilic domain of the complex. The X-ray structure of complex I from Yarrowia lipolytica provides clues supporting the previously proposed two-state stabilization change mechanism, in which ubiquinone redox chemistry induces conformational states and thereby drives proton pumping. The same structural rearrangements may explain the active/deactive transition of complex I implying an integrated mechanistic model for energy conversion and regulation. This article is part of a Special Issue entitled Respiratory complex I, edited by Volker Zickermann and Ulrich Brandt.
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Affiliation(s)
- Christophe Wirth
- Institute for Biochemistry and Molecular Biology, ZBMZ, BIOSS Centre for Biological Signalling Studies, University of Freiburg, Germany
| | - Ulrich Brandt
- Nijmegen Center for Mitochondrial Disorders, Radboud University Medical Center, Nijmegen, The Netherlands; Cluster of Excellence Frankfurt "Macromolecular Complexes, Goethe-University, Germany
| | - Carola Hunte
- Institute for Biochemistry and Molecular Biology, ZBMZ, BIOSS Centre for Biological Signalling Studies, University of Freiburg, Germany.
| | - Volker Zickermann
- Structural Bioenergetics Group, Institute of Biochemistry II, Medical School, Goethe-University, Frankfurt am Main, Germany; Cluster of Excellence Frankfurt "Macromolecular Complexes, Goethe-University, Germany.
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15
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Vartak R, Deng J, Fang H, Bai Y. Redefining the roles of mitochondrial DNA-encoded subunits in respiratory Complex I assembly. Biochim Biophys Acta Mol Basis Dis 2015; 1852:1531-9. [PMID: 25887158 DOI: 10.1016/j.bbadis.2015.04.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 04/01/2015] [Accepted: 04/07/2015] [Indexed: 02/03/2023]
Abstract
Respiratory Complex I deficiency is implicated in numerous degenerative and metabolic diseases. In particular, mutations in several mitochondrial DNA (mtDNA)-encoded Complex I subunits including ND4, ND5 and ND6 have been identified in several neurological diseases. We previously demonstrated that these subunits played essential roles in Complex I assembly which in turn affected mitochondrial function. Here, we carried out a comprehensive study of the Complex I assembly pathway. We identified a new Complex I intermediate containing both membrane and matrix arms at an early assembly stage. We find that lack of the ND6 subunit does not hinder membrane arm formation; instead it recruits ND1 and ND5 enters the intermediate. While ND4 is important for the formation of the newly identified intermediate, the addition of ND5 stabilizes the complex and is required for the critical transition from Complex I to supercomplex assembly. As a result, the Complex I assembly pathway has been redefined in this study.
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Affiliation(s)
- Rasika Vartak
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Janice Deng
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Hezhi Fang
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Yidong Bai
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
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Narayanan M, Leung SA, Inaba Y, Elguindy MM, Nakamaru-Ogiso E. Semiquinone intermediates are involved in the energy coupling mechanism of E. coli complex I. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:681-9. [PMID: 25868873 DOI: 10.1016/j.bbabio.2015.04.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 03/14/2015] [Accepted: 04/05/2015] [Indexed: 11/28/2022]
Abstract
Complex I (NADH:quinone oxidoreductase) is central to cellular aerobic energy metabolism, and its deficiency is involved in many human mitochondrial diseases. Complex I translocates protons across the membrane using electron transfer energy. Semiquinone (SQ) intermediates appearing during catalysis are suggested to be key for the coupling mechanism in complex I. However, the existence of SQ has remained controversial due to the extreme difficulty in detecting unstable and low intensity SQ signals. Here, for the first time with Escherichia coli complex I reconstituted in proteoliposomes, we successfully resolved and characterized three distinct SQ species by EPR. These species include: fast-relaxing SQ (SQNf) with P1/2 (half-saturation power level)>50mW and a wider linewidth (12.8 G); slow-relaxing SQ (SQNs) with P1/2=2-3mW and a 10G linewidth; and very slow-relaxing SQ (SQNvs) with P1/2= ~0.1mW and a 7.5G linewidth. The SQNf signals completely disappeared in the presence of the uncoupler gramicidin D or squamotacin, a potent E. coli complex I inhibitor. The pH dependency of the SQNf signals correlated with the proton-pumping activities of complex I. The SQNs signals were insensitive to gramicidin D, but sensitive to squamotacin. The SQNvs signals were insensitive to both gramicidin D and squamotacin. Our deuterium exchange experiments suggested that SQNf is neutral, while SQNs and SQNvs are anion radicals. The SQNs signals were lost in the ΔNuoL mutant missing transporter module subunits NuoL and NuoM. The roles and relationships of the SQ intermediates in the coupling mechanism are discussed.
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Affiliation(s)
- Madhavan Narayanan
- Johnson Research Foundation, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Steven A Leung
- Johnson Research Foundation, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Yuta Inaba
- Johnson Research Foundation, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Mahmoud M Elguindy
- Johnson Research Foundation, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Eiko Nakamaru-Ogiso
- Johnson Research Foundation, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States.
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Vartak RS, Semwal MK, Bai Y. An update on complex I assembly: the assembly of players. J Bioenerg Biomembr 2014; 46:323-8. [PMID: 25030182 DOI: 10.1007/s10863-014-9564-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Accepted: 07/02/2014] [Indexed: 12/19/2022]
Abstract
Defects in Complex I assembly is one of the emerging underlying causes of severe mitochondrial disorders. The assembly of Complex I has been difficult to understand due to its large size, dual genetic control and the number of proteins involved. Mutations in Complex I subunits as well as assembly factors have been reported to hinder its assembly and give rise to a range of mitochondria disorders. In this review, we summarize the recent progress made in understanding the Complex I assembly pathway. In particularly, we focus on the known as well as novel assembly factors and their role in assembly of Complex I and human disease.
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Affiliation(s)
- Rasika S Vartak
- Department of Cellular and Structural Biology, UT Health Science Center, San Antonio, TX, USA
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18
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Shimada S, Shinzawa-Itoh K, Amano S, Akira Y, Miyazawa A, Tsukihara T, Tani K, Gerle C, Yoshikawa S. Three-dimensional structure of bovine heart NADH: ubiquinone oxidoreductase (complex I) by electron microscopy of a single negatively stained two-dimensional crystal. Microscopy (Oxf) 2014; 63:167-74. [PMID: 24523515 DOI: 10.1093/jmicro/dft082] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Bovine heart NADH:ubiquinone oxidoreductase (complex I), which is the largest (about 1 MDa) membrane protein complex in the mitochondrial respiratory chain, catalyzes the electron transfer from NADH to ubiquinone, coupled with proton pumping. We have crystallized bovine complex I in reconstituted lipid bilayers and obtained a three-dimensional density map by the electron crystallographic analysis of a single negatively stained two-dimensional crystal. The asymmetric unit with dimensions of a = 388 Å, b = 129 Å and γ = 90° contains two molecules and is of P1 symmetry. Structural differences between the two molecules indicate flexibility of the hydrophilic domain relative to the membrane-embedded domain.
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Ibrahim M, Tao Z, Hussain A, Chunlan Y, Ilyas M, Waheed A, Yuan F, Li B, Xie GL. Deciphering the role of Burkholderia cenocepacia membrane proteins in antimicrobial properties of chitosan. Arch Microbiol 2013; 196:9-16. [PMID: 24213809 DOI: 10.1007/s00203-013-0936-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 10/09/2013] [Accepted: 10/24/2013] [Indexed: 10/26/2022]
Abstract
Chitosan, a versatile derivative of chitin, is widely used as an antimicrobial agent either alone or mixed with other natural polymers. Burkholderia cenocepacia is a multidrug-resistant bacteria and difficult to eradicate. Our previous studies shown that chitosan had strong antibacterial activity against B. cenocepacia. In the current study, we have investigated the molecular aspects for the susceptibility of B. cenocepacia in response to chitosan antibacterial activity. We have conducted RNA expression analysis of drug efflux system by RT-PCR, membrane protein profiling by SDS-PAGE, and by LC-MS/MS analysis following the validation of selected membrane proteins by real-time PCR analysis. By RT-PCR analysis, it was found that orf3, orf9, and orf13 were expressed at detectable levels, which were similar to control, while rest of the orf did not express. Moreover, shotgun proteomics analysis revealed 21 proteins in chitosan-treated cells and 16 proteins in control. Among them 4 proteins were detected as shared proteins under control and chitosan-treated cells and 17 proteins as uniquely identified proteins under chitosan-treated cells. Among the catalog of uniquely identified proteins, there were proteins involved in electron transport chain and ATP synthase, metabolism of carbohydrates and adaptation to atypical conditions proteins which indicate that utilization and pattern of chitosan is diverse which might be responsible for its antibacterial effects on bacteria. Moreover, our results showed that RND drug efflux system, which display the ability to transport a variety of structurally unrelated drugs from a cell and consequently are capable of conferring resistance to a diverse range of chemotherapeutic agents, was not determined to play its role in response to chitosan. It might be lipopolysaccharides interaction with chitosan resulted in the destabilization of membrane protein to membrane lyses to cell death. Membrane proteome analysis were also validated by RT-qPCR analysis, which corroborated our results that of membrane proteins.
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Affiliation(s)
- Muhammad Ibrahim
- State Key Laboratory of Rice Biology, Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Ministry of Agriculture, Institute of Biotechnology, Zhejiang University, 388 Yuhangtang Road, Hangzhou, 310058, People's Republic of China
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Sun F, Zhou Q, Pang X, Xu Y, Rao Z. Revealing various coupling of electron transfer and proton pumping in mitochondrial respiratory chain. Curr Opin Struct Biol 2013; 23:526-38. [DOI: 10.1016/j.sbi.2013.06.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 06/13/2013] [Accepted: 06/19/2013] [Indexed: 01/23/2023]
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21
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Peters K, Belt K, Braun HP. 3D Gel Map of Arabidopsis Complex I. FRONTIERS IN PLANT SCIENCE 2013; 4:153. [PMID: 23761796 PMCID: PMC3671202 DOI: 10.3389/fpls.2013.00153] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 05/04/2013] [Indexed: 05/20/2023]
Abstract
Complex I has a unique structure in plants and includes extra subunits. Here, we present a novel study to define its protein constituents. Mitochondria were isolated from Arabidopsis thaliana cell cultures, leaves, and roots. Subunits of complex I were resolved by 3D blue-native (BN)/SDS/SDS-PAGE and identified by mass spectrometry. Overall, 55 distinct proteins were found, seven of which occur in pairs of isoforms. We present evidence that Arabidopsis complex I consists of 49 distinct types of subunits, 40 of which represent homologs of bovine complex I. The nine other subunits represent special proteins absent in the animal linage of eukaryotes, most prominently a group of subunits related to bacterial gamma-type carbonic anhydrases. A GelMap http://www.gelmap.de/arabidopsis-3d-complex-i/ is presented for promoting future complex I research in Arabidopsis thaliana.
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Affiliation(s)
- Katrin Peters
- Institute for Plant Genetics, Faculty of Natural Sciences, Leibniz Universität Hannover, Hannover, Germany
| | - Katharina Belt
- Institute for Plant Genetics, Faculty of Natural Sciences, Leibniz Universität Hannover, Hannover, Germany
| | - Hans-Peter Braun
- Institute for Plant Genetics, Faculty of Natural Sciences, Leibniz Universität Hannover, Hannover, Germany
- *Correspondence: Hans-Peter Braun, Institute for Plant Genetics, Faculty of Natural Sciences, Leibniz Universität Hannover, Herrenhäuser Straße 2, 30419 Hannover, Germany e-mail:
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22
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Hoefs SJ, Rodenburg RJ, Smeitink JA, van den Heuvel LP. Molecular base of biochemical complex I deficiency. Mitochondrion 2012; 12:520-32. [DOI: 10.1016/j.mito.2012.07.106] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Revised: 07/06/2012] [Accepted: 07/10/2012] [Indexed: 12/21/2022]
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23
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Papa S, Martino PL, Capitanio G, Gaballo A, De Rasmo D, Signorile A, Petruzzella V. The oxidative phosphorylation system in mammalian mitochondria. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 942:3-37. [PMID: 22399416 DOI: 10.1007/978-94-007-2869-1_1] [Citation(s) in RCA: 169] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The chapter provides a review of the state of art of the oxidative phosphorylation system in mammalian mitochondria. The sections of the paper deal with: (i) the respiratory chain as a whole: redox centers of the chain and protonic coupling in oxidative phosphorylation (ii) atomic structure and functional mechanism of protonmotive complexes I, III, IV and V of the oxidative phosphorylation system (iii) biogenesis of oxidative phosphorylation complexes: mitochondrial import of nuclear encoded subunits, assembly of oxidative phosphorylation complexes, transcriptional factors controlling biogenesis of the complexes. This advanced knowledge of the structure, functional mechanism and biogenesis of the oxidative phosphorylation system provides a background to understand the pathological impact of genetic and acquired dysfunctions of mitochondrial oxidative phosphorylation.
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Affiliation(s)
- Sergio Papa
- Department of Basic Medical Sciences, University of Bari, Bari, Italy.
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24
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Albracht SPJ, Meijer AJ, Rydström J. Mammalian NADH:ubiquinone oxidoreductase (Complex I) and nicotinamide nucleotide transhydrogenase (Nnt) together regulate the mitochondrial production of H₂O₂--implications for their role in disease, especially cancer. J Bioenerg Biomembr 2011; 43:541-64. [PMID: 21882037 DOI: 10.1007/s10863-011-9381-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Accepted: 08/03/2011] [Indexed: 12/20/2022]
Abstract
Mammalian NADH:ubiquinone oxidoreductase (Complex I) in the mitochondrial inner membrane catalyzes the oxidation of NADH in the matrix. Excess NADH reduces nine of the ten prosthetic groups of the enzyme in bovine-heart submitochondrial particles with a rate of at least 3,300 s⁻¹. This results in an overall NADH→O₂ rate of ca. 150 s⁻¹. It has long been known that the bovine enzyme also has a specific reaction site for NADPH. At neutral pH excess NADPH reduces only three to four of the prosthetic groups in Complex I with a rate of 40 s⁻¹ at 22 °C. The reducing equivalents remain essentially locked in the enzyme because the overall NADPH→O₂ rate (1.4 s⁻¹) is negligible. The physiological significance of the reaction with NADPH is still unclear. A number of recent developments has revived our thinking about this enigma. We hypothesize that Complex I and the Δp-driven nicotinamide nucleotide transhydrogenase (Nnt) co-operate in an energy-dependent attenuation of the hydrogen-peroxide generation by Complex I. This co-operation is thought to be mediated by the NADPH/NADP⁺ ratio in the vicinity of the NADPH site of Complex I. It is proposed that the specific H₂O₂ production by Complex I, and the attenuation of it, is of importance for apoptosis, autophagy and the survival mechanism of a number of cancers. Verification of this hypothesis may contribute to a better understanding of the regulation of these processes.
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Affiliation(s)
- Simon P J Albracht
- Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, NL-1098 XH, Amsterdam, The Netherlands.
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25
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Kinetics and regulation of mammalian NADH-ubiquinone oxidoreductase (Complex I). Biophys J 2010; 99:1426-36. [PMID: 20816054 DOI: 10.1016/j.bpj.2010.06.063] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Revised: 06/14/2010] [Accepted: 06/22/2010] [Indexed: 11/22/2022] Open
Abstract
NADH-ubiquinone oxidoreductase (Complex I, European Commission No. 1.6.5.3) is one of the respiratory complexes that generate the proton-motive force required for the synthesis of ATP in mitochondria. The catalytic mechanism of Complex I has not been well understood, due to the complicated structure of this enzyme. Here, we develop a kinetic model for Complex I that accounts for electron transfer from NADH to ubiquinone through protein-bound prosthetic groups, which is coupled to the translocation of protons across the inner mitochondrial membrane. The model is derived based on the tri-bi enzyme mechanism combined with a simple model of the conformational changes associated with proton transport. To study the catalytic mechanism, parameter values are estimated by analyzing kinetic data. The model is further validated by independent data sets from additional experiments, effectively explaining the effect of pH on enzyme activity. Results imply that matrix pH significantly affects the enzyme turnover processes. The overall kinetic analysis demonstrates a hybrid ping-pong rapid-equilibrium random bi-bi mechanism, consolidating the characteristics from previously reported kinetic mechanisms and data.
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Tocilescu MA, Zickermann V, Zwicker K, Brandt U. Quinone binding and reduction by respiratory complex I. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1883-90. [DOI: 10.1016/j.bbabio.2010.05.009] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2010] [Revised: 05/08/2010] [Accepted: 05/10/2010] [Indexed: 12/12/2022]
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Effects of rotenone and pyridaben on complex I electron transfer and on mitochondrial nitric oxide synthase functional activity. J Bioenerg Biomembr 2010; 42:405-12. [DOI: 10.1007/s10863-010-9309-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Accepted: 08/29/2010] [Indexed: 12/14/2022]
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28
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Ohnishi T, Nakamaru-Ogiso E, Ohnishi ST. A new hypothesis on the simultaneous direct and indirect proton pump mechanisms in NADH-quinone oxidoreductase (complex I). FEBS Lett 2010; 584:4131-7. [PMID: 20816962 DOI: 10.1016/j.febslet.2010.08.039] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Revised: 08/21/2010] [Accepted: 08/29/2010] [Indexed: 02/07/2023]
Abstract
Recently, Sazanov's group reported the X-ray structure of whole complex I [Nature, 465, 441 (2010)], which presented a strong clue for a "piston-like" structure as a key element in an "indirect" proton pump. We have studied the NuoL subunit which has a high sequence similarity to Na(+)/H(+) antiporters, as do the NuoM and N subunits. We constructed 27 site-directed NuoL mutants. Our data suggest that the H(+)/e(-) stoichiometry seems to have decreased from (4H(+)/2e(-)) in the wild-type to approximately (3H(+)/2e(-)) in NuoL mutants. We propose a revised hypothesis that each of the "direct" and the "indirect" proton pumps transports 2H(+) per 2e(-).
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Affiliation(s)
- Tomoko Ohnishi
- Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6059, USA.
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29
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The reaction of NADPH with bovine mitochondrial NADH:ubiquinone oxidoreductase revisited: I. Proposed consequences for electron transfer in the enzyme. J Bioenerg Biomembr 2010; 42:261-78. [PMID: 20628895 DOI: 10.1007/s10863-010-9301-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Accepted: 06/21/2010] [Indexed: 10/19/2022]
Abstract
Bovine NADH:ubiquinone oxidoreductase (Complex I) is the first complex in the mitochondrial respiratory chain. It has long been assumed that it contained only one FMN group. However, as demonstrated in 2003, the intact enzyme contains two FMN groups. The second FMN was proposed to be located in a conserved flavodoxin fold predicted to be present in the PSST subunit. The long-known reaction of Complex I with NADPH differs in many aspects from that with NADH. It was proposed that the second flavin group was specifically involved in the reaction with NADPH. The X-ray structure of the hydrophilic domain of Complex I from Thermus thermophilus (Sazanov and Hinchliffe 2006, Science 311, 1430-1436) disclosed the positions of all redox groups of that enzyme and of the subunits holding them. The PSST subunit indeed contains the predicted flavodoxin fold although it did not contain FMN. Inspired by this structure, the present paper describes a re-evaluation of the enigmatic reactions of the bovine enzyme with NADPH. Published data, as well as new freeze-quench kinetic data presented here, are incompatible with the general opinion that NADPH and NADH react at the same site. Instead, it is proposed that these pyridine nucleotides react at opposite ends of the 90 A long chain of prosthetic groups in Complex I. Ubiquinone is proposed to react with the Fe-S clusters in the TYKY subunit deep inside the hydrophilic domain. A new model for electron transfer in Complex I is proposed. In the accompanying paper this model is compared with the one advocated in current literature.
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Tocilescu MA, Fendel U, Zwicker K, Dröse S, Kerscher S, Brandt U. The role of a conserved tyrosine in the 49-kDa subunit of complex I for ubiquinone binding and reduction. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:625-32. [DOI: 10.1016/j.bbabio.2010.01.029] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Revised: 01/07/2010] [Accepted: 01/25/2010] [Indexed: 10/19/2022]
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Ransac S, Arnarez C, Mazat JP. The flitting of electrons in complex I: a stochastic approach. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:641-8. [PMID: 20230777 DOI: 10.1016/j.bbabio.2010.03.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2009] [Revised: 02/19/2010] [Accepted: 03/06/2010] [Indexed: 12/12/2022]
Abstract
A stochastic approach based on the Gillespie algorithm is particularly well adapted to describe the time course of the redox reactions that occur inside the respiratory chain complexes because they involve the motion of single electrons between the individual unique redox centres of a given complex. We use this approach to describe the molecular functioning of the peripheral arm of complex I based on its known crystallographic structure and the rate constants of electron tunnelling derived from the Moser and Dutton phenomenological equations. There are several possible electrons pathways but we show that most of them take the route defined by the successive sites and redox centres: NADH+ site-FMN-N3-N1b-N4-N5-N6a-N6b-N2-Q site. However, the electrons do not go directly from NADH towards the ubiquinone molecule. They frequently jump back and forth between neighbouring redox centres with the result that the net flux of electrons through complex I (i.e. net number of electrons reducing a ubiquinone) is far smaller than the number of redox reactions which actually occur. While most of the redox centres are reduced in our simulations the degree of reduction can vary according to the individual midpoint potentials. The high turnover number observed in our simulation seems to indicate that, in the whole complex I, one or several slower step(s) follow(s) the redox reactions involved in the peripheral arm. It also appears that the residence time of FMNH* and SQ* (possible producers of ROS) is low (around 4% and between 1.6% and 5% respectively according to the values of the midpoint potentials). We did not find any evidence for a role of N7 which remains mainly reduced in our simulations. The role of N1a is complex and depends upon its midpoint potential. In all cases its presence slightly decreases the life time of the flavosemiquinone species. These simulations demonstrate the interest of this type of model which links the molecular physico-chemistry of the individual redox reactions to the more global level of the reaction, as is observed experimentally.
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Affiliation(s)
- Stéphane Ransac
- Université de Bordeaux 2, Mitochondrial physiopathology laboratory, INSERM U688, Bordeaux, France
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33
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Sharma LK, Lu J, Bai Y. Mitochondrial respiratory complex I: structure, function and implication in human diseases. Curr Med Chem 2009; 16:1266-77. [PMID: 19355884 DOI: 10.2174/092986709787846578] [Citation(s) in RCA: 231] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Mitochondria are ubiquitous organelles in eukaryotic cells whose primary function is to generate energy supplies in the form of ATP through oxidative phosphorylation. As the entry point for most electrons into the respiratory chain, NADH:ubiquinone oxidoreductase, or complex I, is the largest and least understood component of the mitochondrial oxidative phosphorylation system. Substantial progress has been made in recent years in understanding its subunit composition, its assembly, the interaction among complex I and other respiratory components, and its role in oxidative stress and apoptosis. This review provides an updated overview of the structure of complex I, as well as its cellular functions, and discusses the implication of complex I dysfunction in various human diseases.
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Affiliation(s)
- Lokendra K Sharma
- Department of Cellular and Structural Biology, University of Texas Health Sciences Center at San Antonio, San Antonio, TX 78229, USA
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Chapter 1 Visualizing functional flexibility by three-dimensional electron microscopy reconstructing complex I of the mitochondrial respiratory chain. Methods Enzymol 2009; 456:3-27. [PMID: 19348880 DOI: 10.1016/s0076-6879(08)04401-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/06/2023]
Abstract
Complex I is the major entry point in the bacterial and mitochondrial respiratory chain. Structural knowledge of the enzyme is still limited because of its large size and complicated architecture. Only the structure of the hydrophilic domain of a bacterial Complex I has been solved to high resolution by X-ray crystallography. To date, no X-ray structure of the complete enzyme has been reported, and most structural information of the holoenzyme has been obtained by 3-D electron microscopy. In this chapter the methods are described used for determining the 3-D reconstruction of Complex I that revealed for the first time a detailed and reproducible domain structure. Complex I is a highly flexible molecule, and methods for calculating the 3-D reconstruction from electron micrographs must take into account this heterogeneity. The techniques described in this chapter can be modified and adapted for the study of more heterogeneous preparations, such as functionalized Complex I. In addition, these techniques are not restricted to the structure determination of Complex I but are appropriate for the 3-D reconstruction of macromolecular assemblies from electron micrographs when inhomogeneities may be present.
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Zickermann V, Kerscher S, Zwicker K, Tocilescu MA, Radermacher M, Brandt U. Architecture of complex I and its implications for electron transfer and proton pumping. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:574-83. [PMID: 19366614 DOI: 10.1016/j.bbabio.2009.01.012] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Revised: 01/15/2009] [Accepted: 01/15/2009] [Indexed: 11/27/2022]
Abstract
Proton pumping NADH:ubiquinone oxidoreductase (complex I) is the largest and remains by far the least understood enzyme complex of the respiratory chain. It consists of a peripheral arm harbouring all known redox active prosthetic groups and a membrane arm with a yet unknown number of proton translocation sites. The ubiquinone reduction site close to iron-sulfur cluster N2 at the interface of the 49-kDa and PSST subunits has been mapped by extensive site directed mutagenesis. Independent lines of evidence identified electron transfer events during reduction of ubiquinone to be associated with the potential drop that generates the full driving force for proton translocation with a 4H(+)/2e(-) stoichiometry. Electron microscopic analysis of immuno-labelled native enzyme and of a subcomplex lacking the electron input module indicated a distance of 35-60 A of cluster N2 to the membrane surface. Resolution of the membrane arm into subcomplexes showed that even the distal part harbours subunits that are prime candidates to participate in proton translocation because they are homologous to sodium/proton antiporters and contain conserved charged residues in predicted transmembrane helices. The mechanism of redox linked proton translocation by complex I is largely unknown but has to include steps where energy is transmitted over extremely long distances. In this review we compile the available structural information on complex I and discuss implications for complex I function.
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Affiliation(s)
- Volker Zickermann
- Goethe-Universität, Fachbereich Medizin, Molekulare Bioenergetik, ZBC, Theodor-Stern-Kai 7, Haus 26, D-60590 Frankfurt am Main, Germany
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36
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Berrisford JM, Thompson CJ, Sazanov LA. Chemical and NADH-induced, ROS-dependent, cross-linking between subunits of complex I from Escherichia coli and Thermus thermophilus. Biochemistry 2008; 47:10262-70. [PMID: 18771280 DOI: 10.1021/bi801160u] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Complex I of respiratory chains transfers electrons from NADH to ubiquinone, coupled to the translocation of protons across the membrane. Two alternative coupling mechanisms are being discussed, redox-driven or conformation-driven. Using "zero-length" cross-linking reagent and isolated hydrophilic domains of complex I from Escherichia coli and Thermus thermophilus, we show that the pattern of cross-links between subunits changes significantly in the presence of NADH. Similar observations were made previously with intact purified E. coli and bovine complex I. This indicates that, upon reduction with NADH, similar conformational changes are likely to occur in the intact enzyme and in the isolated hydrophilic domain (which can be used for crystallographic studies). Within intact E. coli complex I, the cross-link between the hydrophobic subunits NuoA and NuoJ was abolished in the presence of NADH, indicating that conformational changes extend into the membrane domain, possibly as part of a coupling mechanism. Unexpectedly, in the absence of any chemical cross-linker, incubation of complex I with NADH resulted in covalent cross-links between subunits Nqo4 (NuoCD) and Nqo6 (NuoB), as well as between Nqo6 and Nqo9. Their formation depends on the presence of oxygen and so is likely a result of oxidative damage via reactive oxygen species (ROS) induced cross-linking. In addition, ROS- and metal ion-dependent proteolysis of these subunits (as well as Nqo3) is observed. Fe-S cluster N2 is coordinated between subunits Nqo4 and Nqo6 and could be involved in these processes. Our observations suggest that oxidative damage to complex I in vivo may include not only side-chain modifications but also protein cross-linking and degradation.
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Affiliation(s)
- John M Berrisford
- Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/MRC building, Hills Road, Cambridge CB2 0XY, UK
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37
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Pathak RU, Davey GP. Complex I and energy thresholds in the brain. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:777-82. [DOI: 10.1016/j.bbabio.2008.05.443] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Revised: 05/21/2008] [Accepted: 05/22/2008] [Indexed: 10/22/2022]
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38
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Eukaryotic complex I: functional diversity and experimental systems to unravel the assembly process. Mol Genet Genomics 2008; 280:93-110. [DOI: 10.1007/s00438-008-0350-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2008] [Accepted: 05/01/2008] [Indexed: 10/21/2022]
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Morgan DJ, Sazanov LA. Three-dimensional structure of respiratory complex I from Escherichia coli in ice in the presence of nucleotides. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:711-8. [PMID: 18433710 DOI: 10.1016/j.bbabio.2008.03.023] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Revised: 03/07/2008] [Accepted: 03/25/2008] [Indexed: 11/24/2022]
Abstract
Complex I (NADH:ubiquinone oxidoreductase) is the largest protein complex of bacterial and mitochondrial respiratory chains. The first three-dimensional structure of bacterial complex I in vitrified ice was determined by electron cryo-microscopy and single particle analysis. The structure of the Escherichia coli enzyme incubated with either NAD(+) (as a reference) or NADH was calculated to 35 and 39 A resolution, respectively. The X-ray structure of the peripheral arm of Thermus thermophilus complex I was docked into the reference EM structure. The model obtained indicates that Fe-S cluster N2 is close to the membrane domain interface, allowing for effective electron transfer to membrane-embedded quinone. At the current resolution, the structures in the presence of NAD(+) or NADH are similar. Additionally, side-view class averages were calculated for the negatively stained bovine enzyme. The structures of bovine complex I in the presence of either NAD(+) or NADH also appeared to be similar. These observations indicate that conformational changes upon reduction with NADH, suggested to occur by a range of studies, are smaller than had been thought previously. The model of the entire bacterial complex I could be built from the crystal structures of subcomplexes using the EM envelope described here.
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Affiliation(s)
- David J Morgan
- Medical Research Council, Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, UK
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40
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EXAFS reveals a structural zinc binding site in the bovine NADH-Q oxidoreductase. FEBS Lett 2007; 581:5645-8. [DOI: 10.1016/j.febslet.2007.11.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Revised: 11/07/2007] [Accepted: 11/08/2007] [Indexed: 11/21/2022]
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41
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Flötenmeyer M, Weiss H, Tribet C, Popot JL, Leonard K. The use of amphipathic polymers for cryo electron microscopy of NADH:ubiquinone oxidoreductase (complex I). J Microsc 2007; 227:229-35. [PMID: 17760617 DOI: 10.1111/j.1365-2818.2007.01805.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In the three-dimensional (3D) structure determination of macromolecules, cryo electron microscopy (cryo-EM) is an important method for obtaining micrographs of unstained specimens for the single-particle reconstruction approach. For cryo-EM, proteins are fixed in a frozen hydrated state by quick-freezing in a thin water layer on a holey carbon film. Cryo-EM of detergent-solubilized membrane proteins is hindered by the fact that detergents reduce the surface tension of water, so that it is difficult to control the ice thickness and the distribution of protein. Amphipols are a new class of amphipathic polymers designed to handle membrane proteins in aqueous solutions under particularly mild conditions. Amphipol A8-35 stabilizes NADH:ubiquinone oxidoreductase (complex I) from Neurospora crassa and keeps it water-soluble in the absence of free detergent. Electron microscope images of quick-frozen complex I/A8-35 samples were used for computer-based single-particle averaging and 3D reconstruction, and the reconstruction of unstained frozen-hydrated particles compared with previous detergent-based reconstructions. The potential of amphipols for cryo-EM is discussed.
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Affiliation(s)
- Matthias Flötenmeyer
- European Molecular Biology Laboratory, Meyerhofstrasse 1, D-69117 Heidelberg, Germany
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42
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Vogel RO, Smeitink JAM, Nijtmans LGJ. Human mitochondrial complex I assembly: A dynamic and versatile process. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2007; 1767:1215-27. [PMID: 17854760 DOI: 10.1016/j.bbabio.2007.07.008] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2007] [Revised: 07/24/2007] [Accepted: 07/26/2007] [Indexed: 12/12/2022]
Abstract
One can but admire the intricate way in which biomolecular structures are formed and cooperate to allow proper cellular function. A prominent example of such intricacy is the assembly of the five inner membrane embedded enzymatic complexes of the mitochondrial oxidative phosphorylation (OXPHOS) system, which involves the stepwise combination of >80 subunits and prosthetic groups encoded by both the mitochondrial and nuclear genomes. This review will focus on the assembly of the most complicated OXPHOS structure: complex I (NADH:ubiquinone oxidoreductase, EC 1.6.5.3). Recent studies into complex I assembly in human cells have resulted in several models elucidating a thus far enigmatic process. In this review, special attention will be given to the overlap between the various assembly models proposed in different organisms. Complex I being a complicated structure, its assembly must be prone to some form of coordination. This is where chaperone proteins come into play, some of which may relate complex I assembly to processes such as apoptosis and even immunity.
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Affiliation(s)
- Rutger O Vogel
- Nijmegen Centre for Mitochondrial Disorders, Department of Pediatrics, Radboud University Nijmegen Medical Centre, Geert Grooteplein 10, 6500 HB Nijmegen, The Netherlands
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Lopes R, Solter PF, Sisson DD, Oyama MA, Prosek R. Correlation of mitochondrial protein expression in complexes I to V with natural and induced forms of canine idiopathic dilated cardiomyopathy. Am J Vet Res 2007; 67:971-7. [PMID: 16740089 DOI: 10.2460/ajvr.67.6.971] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To identify qualitative and quantitative differences in cardiac mitochondrial protein expression in complexes I to V between healthy dogs and dogs with natural or induced dilated cardiomyopathy (DCM). SAMPLE POPULATION Left ventricle samples were obtained from 7 healthy dogs, 7 Doberman Pinschers with naturally occurring DCM, and 7 dogs with DCM induced by rapid right ventricular pacing. PROCEDURES Fresh and frozen mitochondrial fractions were isolated from the left ventricular free wall and analyzed by 2-dimensional electrophoresis. Protein spots that increased or decreased in density by 2-fold or greater between groups were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry or quadrupole selecting, quadrupole collision cell, time-of-flight mass spectrometry. RESULTS A total of 22 altered mitochondrial proteins were identified in complexes I to V. Ten and 12 were found in complex I and complexes II to V, respectively. Five were mitochondrial encoded, and 17 were nuclear encoded. Most altered mitochondrial proteins in tissue specimens from dogs with naturally occurring DCM were associated with complexes I and V, whereas in tissue specimens from dogs subjected to rapid ventricular pacing, complexes I and IV were more affected. In the experimentally induced form of DCM, only nuclear-encoded subunits were changed in complex I. In both disease groups, the 22-kd subunit was downregulated. CONCLUSIONS AND CLINICAL RELEVANCE Natural and induced forms of DCM resulted in altered mitochondrial protein expression in complexes I to V. However, subcellular differences between the experimental and naturally occurring forms of DCM may exist.
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Affiliation(s)
- Rosana Lopes
- Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA
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Sherwood S, Hirst J. Investigation of the mechanism of proton translocation by NADH:ubiquinone oxidoreductase (complex I) from bovine heart mitochondria: does the enzyme operate by a Q-cycle mechanism? Biochem J 2006; 400:541-50. [PMID: 16895522 PMCID: PMC1698589 DOI: 10.1042/bj20060766] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Complex I (NADH:ubiquinone oxidoreductase) is the first enzyme of the membrane-bound electron transport chain in mitochondria. It conserves energy, from the reduction of ubiquinone by NADH, as a protonmotive force across the inner membrane, but the mechanism of energy transduction is not known. The structure of the hydrophilic arm of thermophilic complex I supports the idea that proton translocation is driven at (or close to) the point of quinone reduction, rather than at the point of NADH oxidation, with a chain of iron-sulfur clusters transferring electrons between the two active sites. Here, we describe experiments to determine whether complex I, isolated from bovine heart mitochondria, operates via a Q-cycle mechanism analogous to that observed in the cytochrome bc1 complex. No evidence for the 'reductant-induced oxidation' of ubiquinol could be detected; therefore no support for a Q-cycle mechanism was obtained. Unexpectedly, in the presence of NADH, complex I inhibited by either rotenone or piericidin A was found to catalyse the exchange of redox states between different quinone and quinol species, providing a possible route for future investigations into the mechanism of energy transduction.
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Affiliation(s)
- Steven Sherwood
- Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, U.K
| | - Judy Hirst
- Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, U.K
- To whom correspondence should be addressed (email )
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Baranova EA, Holt PJ, Sazanov LA. Projection structure of the membrane domain of Escherichia coli respiratory complex I at 8 A resolution. J Mol Biol 2006; 366:140-54. [PMID: 17157874 DOI: 10.1016/j.jmb.2006.11.026] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2006] [Revised: 10/31/2006] [Accepted: 11/07/2006] [Indexed: 11/25/2022]
Abstract
Respiratory complex I (NADH:ubiquinone oxidoreductase) is an L-shaped multisubunit protein assembly consisting of a hydrophobic membrane arm and a hydrophilic peripheral arm. It catalyses the transfer of two electrons from NADH to quinone coupled to the translocation of four protons across the membrane. Although we have solved recently the crystal structure of the peripheral arm, the structure of the complete enzyme and the coupling mechanism are not yet known. The membrane domain of Escherichia coli complex I consists of seven different subunits with total molecular mass of 258 kDa. It is significantly more stable than the whole enzyme, which allowed us to obtain well-ordered two-dimensional crystals of the domain, belonging to the space group p22(1)2(1). Comparison of the projection map of negatively stained crystals with previously published low-resolution structures indicated that the characteristic curved shape of the membrane domain is remarkably well conserved between bacterial and mitochondrial enzymes, helping us to interpret projection maps in the context of the intact complex. Two pronounced stain-excluding densities at the distal end of the membrane domain are likely to represent the two large antiporter-like subunits NuoL and NuoM. Cryo-electron microscopy on frozen-hydrated crystals allowed us to calculate a projection map at 8 A resolution. About 60 transmembrane alpha-helices, both perpendicular to the membrane plane and tilted, are present within one membrane domain, which is consistent with secondary structure predictions. A possible binding site and access channel for quinone are found at the interface with the peripheral arm. Tentative assignment of individual subunits to the features of the map has been made. The location of subunits NuoL and NuoM at substantial distance from the peripheral arm, which contains all the redox centres of the complex, indicates that conformational changes are likely to play a role in the mechanism of coupling between electron transfer and proton pumping.
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Affiliation(s)
- Ekaterina A Baranova
- Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, UK
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46
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Arteni AA, Zhang P, Battchikova N, Ogawa T, Aro EM, Boekema EJ. Structural characterization of NDH-1 complexes of Thermosynechococcus elongatus by single particle electron microscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1757:1469-75. [PMID: 16844076 DOI: 10.1016/j.bbabio.2006.05.042] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2005] [Revised: 05/23/2006] [Accepted: 05/25/2006] [Indexed: 11/28/2022]
Abstract
The structure of the multifunctional NAD(P)H dehydrogenase type 1 (NDH-1) complexes from cyanobacteria was investigated by growing the wild type and specific ndh His-tag mutants of Thermosynechococcus elongatus BP-1 under different CO(2) conditions, followed by an electron microscopy (EM) analysis of their purified membrane protein complexes. Single particle averaging showed that the complete NDH-1 complex (NDH-1L) is L-shaped, with a relatively short hydrophilic arm. Two smaller complexes were observed, differing only at the tip of the membrane-embedded arm. The smallest one is considered to be similar to NDH-1M, lacking the NdhD1 and NdhF1 subunits. The other fragment, named NDH-1I, is intermediate between NDH-1L and NDH-1M and only lacks a mass compatible with the size of the NdhF1 subunit. Both smaller complexes were observed under low- and high-CO(2) growth conditions, but were much more abundant under the latter conditions. EM characterization of cyanobacterial NDH-1 further showed small numbers of NDH-1 complexes with additional masses. One type of particle has a much longer peripheral arm, similar to the one of NADH: ubiquinone oxidoreductase (complex I) in E. coli and other organisms. This indicates that Thermosynechococcus elongatus must have protein(s) which are structurally homologous to the E. coli NuoE, -F, and -G subunits. Another low-abundance type of particle (NDH-1U) has a second labile hydrophilic arm at the tip of the membrane-embedded arm. This U-shaped particle has not been observed before by EM in a NDH-I preparation.
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Affiliation(s)
- Ana A Arteni
- Department of Biophysical Chemistry, GBB, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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Navarro A, Boveris A. The mitochondrial energy transduction system and the aging process. Am J Physiol Cell Physiol 2006; 292:C670-86. [PMID: 17020935 DOI: 10.1152/ajpcell.00213.2006] [Citation(s) in RCA: 476] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Aged mammalian tissues show a decreased capacity to produce ATP by oxidative phosphorylation due to dysfunctional mitochondria. The mitochondrial content of rat brain and liver is not reduced in aging and the impairment of mitochondrial function is due to decreased rates of electron transfer by the selectively diminished activities of complexes I and IV. Inner membrane H(+) impermeability and F(1)-ATP synthase activity are only slightly affected by aging. Dysfunctional mitochondria in aged rodents are characterized, besides decreased electron transfer and O(2) uptake, by an increased content of oxidation products of phospholipids, proteins and DNA, a decreased membrane potential, and increased size and fragility. Free radical-mediated oxidations are determining factors of mitochondrial dysfunction and turnover, cell apoptosis, tissue function, and lifespan. Inner membrane enzyme activities, such as those of complexes I and IV and mitochondrial nitric oxide synthase, decrease upon aging and afford aging markers. The activities of these three enzymes in mice brain are linearly correlated with neurological performance, as determined by the tightrope and the T-maze tests. The same enzymatic activities correlated positively with mice survival and negatively with the mitochondrial content of lipid and protein oxidation products. Conditions that increase survival, as vitamin E dietary supplementation, caloric restriction, high spontaneous neurological activity, and moderate physical exercise, ameliorate mitochondrial dysfunction in aged brain and liver. The pleiotropic signaling of mitochondrial H(2)O(2) and nitric oxide diffusion to the cytosol seems modified in aged animals and to contribute to the decreased mitochondrial biogenesis in old animals.
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Affiliation(s)
- Ana Navarro
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Plaza Fragela 9, 11003 Cádiz, Spain.
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48
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Pocsfalvi G, Cuccurullo M, Schlosser G, Cacace G, Siciliano RA, Mazzeo MF, Scacco S, Cocco T, Gnoni A, Malorni A, Papa S. Shotgun proteomics for the characterization of subunit composition of mitochondrial complex I. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1757:1438-50. [PMID: 16876106 DOI: 10.1016/j.bbabio.2006.05.037] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2006] [Revised: 04/13/2006] [Accepted: 05/24/2006] [Indexed: 12/21/2022]
Abstract
Here we propose shotgun proteomics as an alternative method to gel-based bottom-up proteomic platform for the structural characterization of mitochondrial NADH:ubiquinone oxidoreductase (complex I). The approach is based on simultaneous identification of subunits after global digestion of the intact complex. Resulting mixture of tryptic peptides is purified, concentrated, separated and online analyzed using nano-scale reverse-phase nano-ESI-MS/MS in a single information dependent acquisition mode. The usefulness of the method is demonstrated in our work on the well described model system of complex I from bovine heart mitochondria. The shotgun method led to the identification and partial sequence characterization of 42 subunits representing more than 95% coverage of the complex. In particular, almost all nuclear (except MLRQ) and 5 mitochondria DNA encoded subunits (except ND4L and ND6) were identified. Furthermore, it was possible to identify 30 co-purified proteins of the inner mitochondrial membrane structurally not belonging to complex I. The method's efficiency is shown by comparing it to two classical 1 D gel-based strategies. Shotgun proteomics is less laborious, significantly faster and requires less sample material with minimal treatment, facilitating the screening for post-translational modifications and quantitative and qualitative differences of complex I subunits in genetic disorders.
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Affiliation(s)
- Gabriella Pocsfalvi
- Proteomic and Biomolecular Mass Spectrometry Centre, Institute of Food Science and Technology, CNR, via Roma 52, a/c, 83100 Avellino, Italy.
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Janssen RJRJ, Nijtmans LG, van den Heuvel LP, Smeitink JAM. Mitochondrial complex I: structure, function and pathology. J Inherit Metab Dis 2006; 29:499-515. [PMID: 16838076 DOI: 10.1007/s10545-006-0362-4] [Citation(s) in RCA: 174] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2006] [Revised: 05/31/2006] [Accepted: 06/01/2006] [Indexed: 10/24/2022]
Abstract
Oxidative phosphorylation (OXPHOS) has a prominent role in energy metabolism of the cell. Being under bigenomic control, correct biogenesis and functioning of the OXPHOS system is dependent on the finely tuned interaction between the nuclear and the mitochondrial genome. This suggests that disturbances of the system can be caused by numerous genetic defects and can result in a variety of metabolic and biochemical alterations. Consequently, OXPHOS deficiencies manifest as a broad clinical spectrum. Complex I, the biggest and most complicated enzyme complex of the OXPHOS system, has been subjected to thorough investigation in recent years. Significant progress has been made in the field of structure, composition, assembly, and pathology. Important gains in the understanding of the Goliath of the OXPHOS system are: exposing the electron transfer mechanism and solving the crystal structure of the peripheral arm, characterization of almost all subunits and some of their functions, and creating models to elucidate the assembly process with concomitant identification of assembly chaperones. Unravelling the intricate mechanisms underlying the functioning of this membrane-bound enzyme complex in health and disease will pave the way for developing adequate diagnostic procedures and advanced therapeutic treatment strategies.
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Affiliation(s)
- Rolf J R J Janssen
- Nijmegen Centre for Mitochondrial Disorders, Laboratory of Paediatrics and Neurology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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50
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Abstract
NADH:quinone oxidoreductase (complex I) pumps protons across the inner membrane of mitochondria or the plasma membrane of many bacteria. Human complex I is involved in numerous pathological conditions and degenerative processes. With 14 central and up to 32 accessory subunits, complex I is among the largest membrane-bound protein assemblies. The peripheral arm of the L-shaped molecule contains flavine mononucleotide and eight or nine iron-sulfur clusters as redox prosthetic groups. Seven of the iron-sulfur clusters form a linear electron transfer chain between flavine and quinone. In most organisms, the seven most hydrophobic subunits forming the core of the membrane arm are encoded by the mitochondrial genome. Most central subunits have evolved from subunits of different hydrogenases and bacterial Na+/H+ antiporters. This evolutionary origin is reflected in three functional modules of complex I. The coupling mechanism of complex I most likely involves semiquinone intermediates that drive proton pumping through redox-linked conformational changes.
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Affiliation(s)
- Ulrich Brandt
- Universität Frankfurt, Fachbereich Medizin, Zentrum der Biologischen Chemie, D-60590 Frankfurt am Main, Germany.
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