1
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Zerihun M, Qvit N. Selective inhibitors targeting Fis1/Mid51 protein-protein interactions protect against hypoxia-induced damage in cardiomyocytes. Front Pharmacol 2023; 14:1275370. [PMID: 38192411 PMCID: PMC10773907 DOI: 10.3389/fphar.2023.1275370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 11/27/2023] [Indexed: 01/10/2024] Open
Abstract
Cardiovascular diseases (CVDs) are the most common non-communicable diseases globally. An estimated 17.9 million people died from CVDs in 2019, representing 32% of all global deaths. Mitochondria play critical roles in cellular metabolic homeostasis, cell survival, and cell death, as well as producing most of the cell's energy. Protein-protein interactions (PPIs) have a significant role in physiological and pathological processes, and aberrant PPIs are associated with various diseases, therefore they are potential drug targets for a broad range of therapeutic areas. Due to their ability to mimic natural interaction motifs and cover relatively larger interaction region, peptides are very promising as PPI inhibitors. To expedite drug discovery, computational approaches are widely used for screening potential lead compounds. Here, we developed peptides that inhibit mitochondrial fission 1 (Fis1)/mitochondrial dynamics 51 kDa (Mid51) PPI to reduce the cellular damage that can lead to various human pathologies, such as CVDs. Based on a rational design approach we developed peptide inhibitors of the Fis1/Mid51 PPI. In silico and in vitro studies were done to evaluate the biological activity and molecular interactions of the peptides. Two peptides, CVP-241 and CVP-242 were identified based on low binding energy and molecular dynamics simulations. These peptides inhibit Fis1/Mid51 PPI (-1324.9 kcal mol-1) in docking calculations (CVP-241, -741.3 kcal mol-1, and CVP-242, -747.4 kcal mol-1), as well as in vitro experimental studies Fis1/Mid51 PPI (KD 0.054 µM) Fis1/Mid51 PPI + CVP-241 (KD 3.43 µM), and Fis1/Mid51 PPI + CVP-242 (KD 44.58 µM). Finally, these peptides have no toxicity to H9c2 cells, and they increase cell viability in cardiomyocytes (H9c2 cells). Consequently, the identified inhibitor peptides could serve as potent molecules in basic research and as leads for therapeutic development.
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Affiliation(s)
| | - Nir Qvit
- The Azrieli Faculty of Medicine in the Galilee, Bar-Ilan University, Safed, Israel
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2
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Nolden KA, Harwig MC, Hill RB. Human Fis1 directly interacts with Drp1 in an evolutionarily conserved manner to promote mitochondrial fission. J Biol Chem 2023; 299:105380. [PMID: 37866629 PMCID: PMC10694664 DOI: 10.1016/j.jbc.2023.105380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Revised: 09/30/2023] [Accepted: 10/11/2023] [Indexed: 10/24/2023] Open
Abstract
Mitochondrial fission protein 1 (Fis1) and dynamin-related protein 1 (Drp1) are the only two proteins evolutionarily conserved for mitochondrial fission, and directly interact in Saccharomyces cerevisiae to facilitate membrane scission. However, it remains unclear if a direct interaction is conserved in higher eukaryotes as other Drp1 recruiters, not present in yeast, are known. Using NMR, differential scanning fluorimetry, and microscale thermophoresis, we determined that human Fis1 directly interacts with human Drp1 (KD = 12-68 μM), and appears to prevent Drp1 assembly, but not GTP hydrolysis. Similar to yeast, the Fis1-Drp1 interaction appears governed by two structural features of Fis1: its N-terminal arm and a conserved surface. Alanine scanning mutagenesis of the arm identified both loss-of-function and gain-of-function alleles with mitochondrial morphologies ranging from highly elongated (N6A) to highly fragmented (E7A), demonstrating a profound ability of Fis1 to govern morphology in human cells. An integrated analysis identified a conserved Fis1 residue, Y76, that upon substitution to alanine, but not phenylalanine, also caused highly fragmented mitochondria. The similar phenotypic effects of the E7A and Y76A substitutions, along with NMR data, support that intramolecular interactions occur between the arm and a conserved surface on Fis1 to promote Drp1-mediated fission as in S. cerevisiae. These findings indicate that some aspects of Drp1-mediated fission in humans derive from direct Fis1-Drp1 interactions that are conserved across eukaryotes.
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Affiliation(s)
- Kelsey A Nolden
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Megan C Harwig
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - R Blake Hill
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
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3
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Ihenacho UK, Toro R, Mansour RH, Hill RB. A conserved, noncanonical insert in FIS1 mediates TBC1D15 and DRP1 recruitment for mitochondrial fission. J Biol Chem 2023; 299:105303. [PMID: 37777154 PMCID: PMC10641528 DOI: 10.1016/j.jbc.2023.105303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 08/22/2023] [Accepted: 09/04/2023] [Indexed: 10/02/2023] Open
Abstract
Mitochondrial fission protein 1 (FIS1) is conserved in all eukaryotes, yet its function in metazoans is thought divergent. Structure-based sequence alignments of FIS1 revealed a conserved, but noncanonical, three-residue insert in its first tetratricopeptide repeat (TPR) suggesting a conserved function. In vertebrates, this insert is serine (S45), lysine (K46), and tyrosine (Y47). To determine the biological role of the "SKY insert," three variants were tested in HCT116 cells for altered mitochondrial morphology and recruitment of fission mechanoenzyme DRP1 and mitophagic adaptor TBC1D15. Similar to ectopically expressed wildtype FIS1, substitution of the SKY insert with alanine (AAA) fragmented mitochondria into perinuclear clumps associated with increased mitochondrial DRP1. In contrast, deletion variants (either ∆SKY or ∆SKYD49G) elongated mitochondrial networks with reduced mitochondrial recruitment of DRP1, despite DRP1 coimmunoprecipitates being highly enriched with ΔSKY variants. Ectopic wildtype FIS1 drove co-expressed YFP-TBC1D15 entirely from the cytoplasm to mitochondria as punctate structures concomitant with enhanced mitochondrial DRP1 recruitment. YFP-TBC1D15 co-expressed with the AAA variant further enhanced mitochondrial DRP1 recruitment, indicating a gain of function. In contrast, YFP-TBC1D15 co-expressed with deletion variants impaired mitochondrial DRP1 and YFP-TBC1D15 recruitment; however, mitochondrial fragmentation was restored. These phenotypes were not due to misfolding or poor expression of FIS1 variants, although ∆SKYD49G induced conformational heterogeneity that is lost upon deletion of the regulatory Fis1 arm, indicating SKY-arm interactions. Collectively, these results support a unifying model whereby FIS1 activity is effectively governed by intramolecular interactions between its regulatory arm and a noncanonical TPR insert that is conserved across eukaryotes.
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Affiliation(s)
- Ugochukwu K Ihenacho
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Rafael Toro
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Rana H Mansour
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - R Blake Hill
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
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4
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He J, Liu K, Wu Y, Zhao C, Yan S, Chen JH, Hu L, Wang D, Zheng F, Wei W, Xu C, Huang C, Liu X, Yao X, Ding L, Fang Z, Tang AH, Fu C. The AAA-ATPase Yta4/ATAD1 interacts with the mitochondrial divisome to inhibit mitochondrial fission. PLoS Biol 2023; 21:e3002247. [PMID: 37590302 PMCID: PMC10465003 DOI: 10.1371/journal.pbio.3002247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 08/29/2023] [Accepted: 07/12/2023] [Indexed: 08/19/2023] Open
Abstract
Mitochondria are in a constant balance of fusion and fission. Excessive fission or deficient fusion leads to mitochondrial fragmentation, causing mitochondrial dysfunction and physiological disorders. How the cell prevents excessive fission of mitochondria is not well understood. Here, we report that the fission yeast AAA-ATPase Yta4, which is the homolog of budding yeast Msp1 responsible for clearing mistargeted tail-anchored (TA) proteins on mitochondria, plays a critical role in preventing excessive mitochondrial fission. The absence of Yta4 leads to mild mitochondrial fragmentation in a Dnm1-dependent manner but severe mitochondrial fragmentation upon induction of mitochondrial depolarization. Overexpression of Yta4 delocalizes the receptor proteins of Dnm1, i.e., Fis1 (a TA protein) and Mdv1 (the bridging protein between Fis1 and Dnm1), from mitochondria and reduces the localization of Dnm1 to mitochondria. The effect of Yta4 overexpression on Fis1 and Mdv1, but not Dnm1, depends on the ATPase and translocase activities of Yta4. Moreover, Yta4 interacts with Dnm1, Mdv1, and Fis1. In addition, Yta4 competes with Dnm1 for binding Mdv1 and decreases the affinity of Dnm1 for GTP and inhibits Dnm1 assembly in vitro. These findings suggest a model, in which Yta4 inhibits mitochondrial fission by inhibiting the function of the mitochondrial divisome composed of Fis1, Mdv1, and Dnm1. Therefore, the present work reveals an uncharacterized molecular mechanism underlying the inhibition of mitochondrial fission.
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Affiliation(s)
- Jiajia He
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Anhui Key Laboratory of Cellular Dynamics and Chemical Biology & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Ke Liu
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Anhui Key Laboratory of Cellular Dynamics and Chemical Biology & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Yifan Wu
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Chenhui Zhao
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Shuaijie Yan
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Jia-Hui Chen
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Institute of Artificial Intelligence, Hefei Comprehensive National Science Center, Hefei, China
| | - Lizhu Hu
- Anhui Province Key Laboratory of Medical Physics and Technology, Institute of Health and Medical Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, China
| | - Dongmei Wang
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Fan Zheng
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Wenfan Wei
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Chao Xu
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Anhui Key Laboratory of Cellular Dynamics and Chemical Biology & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Chengdong Huang
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Anhui Key Laboratory of Cellular Dynamics and Chemical Biology & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Xing Liu
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Anhui Key Laboratory of Cellular Dynamics and Chemical Biology & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Xuebiao Yao
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Anhui Key Laboratory of Cellular Dynamics and Chemical Biology & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Lijun Ding
- Center for Reproductive Medicine, Department of Obstetrics and Gynecology, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
| | - Zhiyou Fang
- Anhui Province Key Laboratory of Medical Physics and Technology, Institute of Health and Medical Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, China
| | - Ai-Hui Tang
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Institute of Artificial Intelligence, Hefei Comprehensive National Science Center, Hefei, China
| | - Chuanhai Fu
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Anhui Key Laboratory of Cellular Dynamics and Chemical Biology & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, China
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5
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Nolden KA, Harwig MC, Hill RB. Human Fis1 directly interacts with Drp1 in an evolutionarily conserved manner to promote mitochondrial fission. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.03.539292. [PMID: 37205551 PMCID: PMC10187221 DOI: 10.1101/2023.05.03.539292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Mitochondrial Fission Protein 1 (Fis1) and Dynamin Related Protein 1 (Drp1) are the only two proteins evolutionarily conserved for mitochondrial fission, and directly interact in S. cerevisiae to facilitate membrane scission. However, it remains unclear if a direct interaction is conserved in higher eukaryotes as other Drp1 recruiters, not present in yeast, are known. Using NMR, differential scanning fluorimetry, and microscale thermophoresis, we determined that human Fis1 directly interacts with human Drp1 ( K D = 12-68 µM), and appears to prevent Drp1 assembly, but not GTP hydrolysis. Similar to yeast, the Fis1-Drp1 interaction appears governed by two structural features of Fis1: its N-terminal arm and a conserved surface. Alanine scanning mutagenesis of the arm identified both loss- and gain-of-function alleles with mitochondrial morphologies ranging from highly elongated (N6A) to highly fragmented (E7A) demonstrating a profound ability of Fis1 to govern morphology in human cells. An integrated analysis identified a conserved Fis1 residue, Y76, that upon substitution to alanine, but not phenylalanine, also caused highly fragmented mitochondria. The similar phenotypic effects of the E7A and Y76A substitutions, along with NMR data, support that intramolecular interactions occur between the arm and a conserved surface on Fis1 to promote Drp1-mediated fission as in S. cerevisiae . These findings indicate that some aspects of Drp1-mediated fission in humans derive from direct Fis1-Drp1 interactions that are conserved across eukaryotes.
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6
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Egner JM, Nolden KA, Harwig MC, Bonate RP, De Anda J, Tessmer MH, Noey EL, Ihenacho UK, Liu Z, Peterson FC, Wong GCL, Widlansky ME, Hill RB. Structural studies of human fission protein FIS1 reveal a dynamic region important for GTPase DRP1 recruitment and mitochondrial fission. J Biol Chem 2022; 298:102620. [PMID: 36272645 PMCID: PMC9747602 DOI: 10.1016/j.jbc.2022.102620] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 09/27/2022] [Accepted: 09/29/2022] [Indexed: 11/07/2022] Open
Abstract
Fission protein 1 (FIS1) and dynamin-related protein 1 (DRP1) were initially described as being evolutionarily conserved for mitochondrial fission, yet in humans the role of FIS1 in this process is unclear and disputed by many. In budding yeast where Fis1p helps to recruit the DRP1 ortholog from the cytoplasm to mitochondria for fission, an N-terminal "arm" of Fis1p is required for function. The yeast Fis1p arm interacts intramolecularly with a conserved tetratricopeptide repeat core and governs in vitro interactions with yeast DRP1. In human FIS1, NMR and X-ray structures show different arm conformations, but its importance for human DRP1 recruitment is unknown. Here, we use molecular dynamics simulations and comparisons to experimental NMR chemical shifts to show the human FIS1 arm can adopt an intramolecular conformation akin to that observed with yeast Fis1p. This finding is further supported through intrinsic tryptophan fluorescence and NMR experiments on human FIS1 with and without the arm. Using NMR, we observed the human FIS1 arm is also sensitive to environmental changes. We reveal the importance of these findings in cellular studies where removal of the FIS1 arm reduces DRP1 recruitment and mitochondrial fission similar to the yeast system. Moreover, we determined that expression of mitophagy adapter TBC1D15 can partially rescue arm-less FIS1 in a manner reminiscent of expression of the adapter Mdv1p in yeast. These findings point to conserved features of FIS1 important for its activity in mitochondrial morphology. More generally, other tetratricopeptide repeat-containing proteins are flanked by disordered arms/tails, suggesting possible common regulatory mechanisms.
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Affiliation(s)
- John M Egner
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Kelsey A Nolden
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Megan Cleland Harwig
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Ryan P Bonate
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Jaime De Anda
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, California, USA
| | - Maxx H Tessmer
- Department of Microbiology & Immunology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Elizabeth L Noey
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Ugochukwu K Ihenacho
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Ziwen Liu
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, California, USA
| | - Francis C Peterson
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Gerard C L Wong
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, California, USA
| | - Michael E Widlansky
- Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - R Blake Hill
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
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7
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Manousaki A, Bagnall J, Spiller D, Balarezo-Cisneros LN, White M, Delneri D. Quantitative Characterisation of Low Abundant Yeast Mitochondrial Proteins Reveals Compensation for Haplo-Insufficiency in Different Environments. Int J Mol Sci 2022; 23:8532. [PMID: 35955668 PMCID: PMC9369417 DOI: 10.3390/ijms23158532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 07/15/2022] [Accepted: 07/25/2022] [Indexed: 02/05/2023] Open
Abstract
The quantification of low abundant membrane-binding proteins such as transcriptional factors and chaperones has proven difficult, even with the most sophisticated analytical technologies. Here, we exploit and optimise the non-invasive Fluorescence Correlation Spectroscopy (FCS) for the quantitation of low abundance proteins, and as proof of principle, we choose two interacting proteins involved in the fission of mitochondria in yeast, Fis1p and Mdv1p. In Saccharomyces cerevisiae, the recruitment of Fis1p and Mdv1p to mitochondria is essential for the scission of the organelles and the retention of functional mitochondrial structures in the cell. We use FCS in single GFP-labelled live yeast cells to quantify the protein abundance in homozygote and heterozygote cells and to investigate the impact of the environments on protein copy number, bound/unbound protein state and mobility kinetics. Both proteins were observed to localise predominantly at mitochondrial structures, with the Mdv1p bound state increasing significantly in a strictly respiratory environment. Moreover, a compensatory mechanism that controls Fis1p abundance upon deletion of one allele was observed in Fis1p but not in Mdv1p, suggesting differential regulation of Fis1p and Mdv1p protein expression.
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Affiliation(s)
- Alkisti Manousaki
- Manchester Institute of Biotechnology, Faculty of Biology, Medicine and Health, The University of Manchester, 131 Princess Street, Manchester M1 7DN, UK; (A.M.); (L.N.B.-C.)
- Division of Evolution and Genomic Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - James Bagnall
- Division of Diabetes, Endocrinology and Gastroenterology Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Oxford Road, Manchester M13 9PT, UK;
| | - David Spiller
- Platform Sciences, Enabling Technologies & Infrastructure, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Oxford Road, Manchester M13 9PT, UK;
| | - Laura Natalia Balarezo-Cisneros
- Manchester Institute of Biotechnology, Faculty of Biology, Medicine and Health, The University of Manchester, 131 Princess Street, Manchester M1 7DN, UK; (A.M.); (L.N.B.-C.)
- Division of Evolution and Genomic Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Michael White
- Division of Molecular and Cellular Function, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Oxford Road, Manchester M13 9PT, UK;
| | - Daniela Delneri
- Manchester Institute of Biotechnology, Faculty of Biology, Medicine and Health, The University of Manchester, 131 Princess Street, Manchester M1 7DN, UK; (A.M.); (L.N.B.-C.)
- Division of Evolution and Genomic Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
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8
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Ihenacho UK, Meacham KA, Harwig MC, Widlansky ME, Hill RB. Mitochondrial Fission Protein 1: Emerging Roles in Organellar Form and Function in Health and Disease. Front Endocrinol (Lausanne) 2021; 12:660095. [PMID: 33841340 PMCID: PMC8027123 DOI: 10.3389/fendo.2021.660095] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 03/05/2021] [Indexed: 12/13/2022] Open
Abstract
Mitochondrial fission protein 1 (Fis1) was identified in yeast as being essential for mitochondrial division or fission and subsequently determined to mediate human mitochondrial and peroxisomal fission. Yet, its exact functions in humans, especially in regard to mitochondrial fission, remains an enigma as genetic deletion of Fis1 elongates mitochondria in some cell types, but not others. Fis1 has also been identified as an important component of apoptotic and mitophagic pathways suggesting the protein may have multiple, essential roles. This review presents current perspectives on the emerging functions of Fis1 and their implications in human health and diseases, with an emphasis on Fis1's role in both endocrine and neurological disorders.
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Affiliation(s)
| | - Kelsey A. Meacham
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Megan Cleland Harwig
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Michael E. Widlansky
- Department of Medicine, Division of Cardiovascular Medicine, Medical College of Wisconsin, Milwaukee, WI, United States
| | - R. Blake Hill
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI, United States
- *Correspondence: R. Blake Hill,
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9
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Yu R, Lendahl U, Nistér M, Zhao J. Regulation of Mammalian Mitochondrial Dynamics: Opportunities and Challenges. Front Endocrinol (Lausanne) 2020; 11:374. [PMID: 32595603 PMCID: PMC7300174 DOI: 10.3389/fendo.2020.00374] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 05/12/2020] [Indexed: 01/01/2023] Open
Abstract
Mitochondria are highly dynamic organelles and important for a variety of cellular functions. They constantly undergo fission and fusion events, referred to as mitochondrial dynamics, which affects the shape, size, and number of mitochondria in the cell, as well as mitochondrial subcellular transport, mitochondrial quality control (mitophagy), and programmed cell death (apoptosis). Dysfunctional mitochondrial dynamics is associated with various human diseases. Mitochondrial dynamics is mediated by a set of mitochondria-shaping proteins in both yeast and mammals. In this review, we describe recent insights into the potential molecular mechanisms underlying mitochondrial fusion and fission, particularly highlighting the coordinating roles of different mitochondria-shaping proteins in the processes, as well as the roles of the endoplasmic reticulum (ER), the actin cytoskeleton and membrane phospholipids in the regulation of mitochondrial dynamics. We particularly focus on emerging roles for the mammalian mitochondrial proteins Fis1, Mff, and MIEFs (MIEF1 and MIEF2) in regulating the recruitment of the cytosolic Drp1 to the surface of mitochondria and how these proteins, especially Fis1, mediate crosstalk between the mitochondrial fission and fusion machineries. In summary, this review provides novel insights into the molecular mechanisms of mammalian mitochondrial dynamics and the involvement of these mechanisms in apoptosis and autophagy.
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Affiliation(s)
- Rong Yu
- Department of Oncology-Pathology, Karolinska Institutet, Karolinska University Hospital Solna, Stockholm, Sweden
| | - Urban Lendahl
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Monica Nistér
- Department of Oncology-Pathology, Karolinska Institutet, Karolinska University Hospital Solna, Stockholm, Sweden
- *Correspondence: Monica Nistér
| | - Jian Zhao
- Department of Oncology-Pathology, Karolinska Institutet, Karolinska University Hospital Solna, Stockholm, Sweden
- Jian Zhao
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10
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Yu R, Jin SB, Lendahl U, Nistér M, Zhao J. Human Fis1 regulates mitochondrial dynamics through inhibition of the fusion machinery. EMBO J 2019; 38:e99748. [PMID: 30842096 PMCID: PMC6463211 DOI: 10.15252/embj.201899748] [Citation(s) in RCA: 166] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 01/25/2019] [Accepted: 01/29/2019] [Indexed: 12/27/2022] Open
Abstract
Mitochondrial dynamics is important for life. At center stage for mitochondrial dynamics, the balance between mitochondrial fission and fusion is a set of dynamin-related GTPases that drive mitochondrial fission and fusion. Fission is executed by the GTPases Drp1 and Dyn2, whereas the GTPases Mfn1, Mfn2, and OPA1 promote fusion. Recruitment of Drp1 to mitochondria is a critical step in fission. In yeast, Fis1p recruits the Drp1 homolog Dnm1p to mitochondria through Mdv1p and Caf4p, but whether human Fis1 (hFis1) promotes fission through a similar mechanism as in yeast is not established. Here, we show that hFis1-mediated mitochondrial fragmentation occurs in the absence of Drp1 and Dyn2, suggesting that they are dispensable for hFis1 function. hFis1 instead binds to Mfn1, Mfn2, and OPA1 and inhibits their GTPase activity, thus blocking the fusion machinery. Consistent with this, disruption of the fusion machinery in Drp1-/- cells phenocopies the fragmentation phenotype induced by hFis1 overexpression. In sum, our data suggest a novel role for hFis1 as an inhibitor of the fusion machinery, revealing an important functional evolutionary divergence between yeast and mammalian Fis1 proteins.
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Affiliation(s)
- Rong Yu
- Department of Oncology-Pathology, Karolinska Institutet, Karolinska University Hospital Solna, Stockholm, Sweden
| | - Shao-Bo Jin
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Urban Lendahl
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Monica Nistér
- Department of Oncology-Pathology, Karolinska Institutet, Karolinska University Hospital Solna, Stockholm, Sweden
| | - Jian Zhao
- Department of Oncology-Pathology, Karolinska Institutet, Karolinska University Hospital Solna, Stockholm, Sweden
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11
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Elfawy HA, Das B. Crosstalk between mitochondrial dysfunction, oxidative stress, and age related neurodegenerative disease: Etiologies and therapeutic strategies. Life Sci 2018; 218:165-184. [PMID: 30578866 DOI: 10.1016/j.lfs.2018.12.029] [Citation(s) in RCA: 189] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 12/10/2018] [Accepted: 12/15/2018] [Indexed: 12/21/2022]
Abstract
Mitochondrial function is vital for normal cellular processes. Mitochondrial damage and oxidative stress have been greatly implicated in the progression of aging, along with the pathogenesis of age-related neurodegenerative diseases (NDs), such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. Although antioxidant therapy has been proposed for the prevention and treatment of age-related NDs, unraveling the molecular mechanisms of mitochondrial dysfunction can lead to significant progress in the development of effective treatments against such diseases. Aging is associated with the generation and accumulation of reactive oxygen species (ROS) that are the major contributors to oxidative stress. Oxidative stress is caused because of the imbalance between the production of ROS and their oxidation, which can affect the mitochondrial respiratory chain function, thereby altering the membrane permeability and calcium homeostasis, along with increasing the heteroplasmic mtDNA and weakening the mitochondrial defense systems. Mitochondrial dysfunction mainly affects mitochondrial biogenesis and dynamics that are prominent in several age-related NDs. Mitochondrial dysfunction has a crucial role in the pathophysiology of age-related NDs. Several mitochondria targeted strategies, such as enhancing the antioxidant bioavailability via novel delivery systems, identifying unique mitochondrial proteins as specific drug targets, investigating the signaling pathways of mitochondrial biogenesis and dynamics, and identifying effective natural products are potentially effective to counteract mitochondrial dysfunction-related NDs.
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Affiliation(s)
- Hasnaa A Elfawy
- School of Biotechnology, KIIT deemed to be University, Campus XI, Bhubaneswar 751024, Odisha, India
| | - Biswadeep Das
- School of Biotechnology, KIIT deemed to be University, Campus XI, Bhubaneswar 751024, Odisha, India.
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12
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Tartas A, Zarkadas C, Palaiomylitou M, Gounalaki N, Tzamarias D, Vlassi M. Ssn6-Tup1 global transcriptional co-repressor: Role of the N-terminal glutamine-rich region of Ssn6. PLoS One 2017; 12:e0186363. [PMID: 29053708 PMCID: PMC5650148 DOI: 10.1371/journal.pone.0186363] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 09/29/2017] [Indexed: 11/19/2022] Open
Abstract
The Ssn6-Tup1 complex is a general transcriptional co-repressor formed by the interaction of Ssn6, a tetratricopeptide repeat (TPR) protein, with the Tup1 repressor. We have previously shown that the N-terminal domain of Ssn6 comprising TPRs 1 to 3 is necessary and sufficient for this interaction and that TPR1 plays critical role. In a subsequent study, we provided evidence that in the absence of Tup1, TPR1 is susceptible to proteolysis and that conformational change(s) accompany the Ssn6-Tup1 complex formation. In this study, we address the question whether the N-terminal non-TPR, glutamine-rich tail of Ssn6 (NTpolyQ), plays any role in the Ssn6/Tup1 association. Our biochemical and yeast-two-hybrid data show that truncation/deletion of the NTpolyQ domain of Ssn6 results in its self association and prevents Tup1 interaction. These results combined with in silico modeling data imply a major role of the NTpolyQ tail of Ssn6 in regulating its interaction with Tup1.
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Affiliation(s)
- Athanassios Tartas
- Institute of Biosciences & Applications, National Centre for Scientific Research “Demokritos”, Ag. Paraskevi Attikis, Athens, Greece
| | - Christoforos Zarkadas
- Institute of Biosciences & Applications, National Centre for Scientific Research “Demokritos”, Ag. Paraskevi Attikis, Athens, Greece
| | - Maria Palaiomylitou
- Institute of Biosciences & Applications, National Centre for Scientific Research “Demokritos”, Ag. Paraskevi Attikis, Athens, Greece
| | - Niki Gounalaki
- Institute of Molecular Biology & Biotechnology, Foundation for Research and Technology, Heraklion, Crete, Greece
| | - Dimitris Tzamarias
- Biology Department, University of Crete, Heraklion, Crete, Greece
- * E-mail: (MV); (DT)
| | - Metaxia Vlassi
- Institute of Biosciences & Applications, National Centre for Scientific Research “Demokritos”, Ag. Paraskevi Attikis, Athens, Greece
- * E-mail: (MV); (DT)
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13
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Bakkum AL, Hill RB. Removal of a consensus proline is not sufficient to allow tetratricopeptide repeat oligomerization. Protein Sci 2017; 26:1974-1983. [PMID: 28707340 DOI: 10.1002/pro.3234] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 07/07/2017] [Accepted: 07/07/2017] [Indexed: 11/10/2022]
Abstract
Tetratricopeptide repeat (TPR) domains are ubiquitous protein interaction domains that adopt a modular antiparallel array of α-helices. The TPR fold typically adopts a monomeric state, and consensus TPRs sequences successfully fold into the expected monomeric topology. The versatility of the TPR fold also supports different quaternary structures, which may function as regulatory switches. One example is yeast mitochondrial fission 1 (Fis1) that appears to interconvert between monomer and dimer states in regulating division of peroxisomes and mitochondria. Whether human Fis1 can also interconvert like the yeast molecule is unknown. A TPR consensus proline residue present in human Fis1 is absent in the yeast molecule and, when added, prevents yeast Fis1 dimerization suggesting that the TPR consensus proline might have persisted to prevent TPR oligomerization. Here, we address this question with human Fis1 and the consensus TPR protein CTPR3. We demonstrate that human Fis1 does not form a noncovalent dimer via its TPR domain, despite conditions that favor dimerization of the yeast protein. We also show that the presence of the consensus proline is not sufficient to forbid TPR dimerization. Lastly, an analysis of all available TPR protein structures (22 nonredundant structures, totaling 64 TPRs-42 with the consensus proline and 22 without) revealed that the consensus proline is not necessary for turn formation, but does favor shorter turns. This work suggests the TPR consensus proline is not to prevent oligomerization, but to favor tight turns between repeats.
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Affiliation(s)
- Amber L Bakkum
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, 53226
| | - R Blake Hill
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, 53226
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14
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Abstract
The highly regulated processes of mitochondrial fusion (joining), fission (division) and trafficking, collectively called mitochondrial dynamics, determine cell-type specific morphology, intracellular distribution and activity of these critical organelles. Mitochondria are critical for cardiac function, while their structural and functional abnormalities contribute to several common cardiovascular diseases, including heart failure (HF). The tightly balanced mitochondrial fusion and fission determine number, morphology and activity of these multifunctional organelles. Although the intracellular architecture of mature cardiomyocytes greatly restricts mitochondrial dynamics, this process occurs in the adult human heart. Fusion and fission modulate multiple mitochondrial functions, ranging from energy and reactive oxygen species production to Ca(2+) homeostasis and cell death, allowing the heart to respond properly to body demands. Tightly controlled balance between fusion and fission is of utmost importance in the high energy-demanding cardiomyocytes. A shift toward fission leads to mitochondrial fragmentation, while a shift toward fusion results in the formation of enlarged mitochondria and in the fusion of damaged mitochondria with healthy organelles. Mfn1, Mfn2 and OPA1 constitute the core machinery promoting mitochondrial fusion, whereas Drp1, Fis1, Mff and MiD49/51 are the core components of fission machinery. Growing evidence suggests that fusion/fission factors in adult cardiomyocytes play essential noncanonical roles in cardiac development, Ca(2+) signaling, mitochondrial quality control and cell death. Impairment of this complex circuit causes cardiomyocyte dysfunction and death contributing to heart injury culminating in HF. Pharmacological targeting of components of this intricate network may be a novel therapeutic modality for HF treatment.
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15
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Campos JC, Bozi LHM, Bechara LRG, Lima VM, Ferreira JCB. Mitochondrial Quality Control in Cardiac Diseases. Front Physiol 2016; 7:479. [PMID: 27818636 PMCID: PMC5073139 DOI: 10.3389/fphys.2016.00479] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 10/05/2016] [Indexed: 01/08/2023] Open
Abstract
Disruption of mitochondrial homeostasis is a hallmark of cardiac diseases. Therefore, maintenance of mitochondrial integrity through different surveillance mechanisms is critical for cardiomyocyte survival. In this review, we discuss the most recent findings on the central role of mitochondrial quality control processes including regulation of mitochondrial redox balance, aldehyde metabolism, proteostasis, dynamics, and clearance in cardiac diseases, highlighting their potential as therapeutic targets.
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Affiliation(s)
- Juliane C Campos
- Department of Anatomy, Institute of Biomedical Sciences, University of Sao Paulo Sao Paulo, Brazil
| | - Luiz H M Bozi
- Department of Anatomy, Institute of Biomedical Sciences, University of Sao Paulo Sao Paulo, Brazil
| | - Luiz R G Bechara
- Department of Anatomy, Institute of Biomedical Sciences, University of Sao Paulo Sao Paulo, Brazil
| | - Vanessa M Lima
- Department of Anatomy, Institute of Biomedical Sciences, University of Sao Paulo Sao Paulo, Brazil
| | - Julio C B Ferreira
- Department of Anatomy, Institute of Biomedical Sciences, University of Sao Paulo Sao Paulo, Brazil
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16
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Koppenol-Raab M, Harwig MC, Posey AE, Egner JM, MacKenzie KR, Hill RB. A Targeted Mutation Identified through pKa Measurements Indicates a Postrecruitment Role for Fis1 in Yeast Mitochondrial Fission. J Biol Chem 2016; 291:20329-44. [PMID: 27496949 DOI: 10.1074/jbc.m116.724005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Indexed: 12/25/2022] Open
Abstract
The tail-anchored protein Fis1 is implicated as a passive tether in yeast mitochondrial fission. We probed the functional role of Fis1 Glu-78, whose elevated side chain pKa suggests participation in protein interactions. Fis1 binds partners Mdv1 or Dnm1 tightly, but mutation E78A weakens Fis1 interaction with Mdv1, alters mitochondrial morphology, and abolishes fission in a growth assay. In fis1Δ rescue experiments, Fis1-E78A causes a novel localization pattern in which Dnm1 uniformly coats the mitochondria. By contrast, Fis1-E78A at lower expression levels recruits Dnm1 into mitochondrial punctate structures but fails to support normal fission. Thus, Fis1 makes multiple interactions that support Dnm1 puncta formation and may be essential after this step, supporting a revised model for assembly of the mitochondrial fission machinery. The insights gained by mutating a residue with a perturbed pKa suggest that side chain pKa values inferred from routine NMR sample pH optimization could provide useful leads for functional investigations.
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Affiliation(s)
| | - Megan Cleland Harwig
- the Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, and
| | - Ammon E Posey
- From the Department of Biology and the Program in Molecular Biophysics, Johns Hopkins University, Baltimore, Maryland 21218
| | - John M Egner
- the Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, and
| | - Kevin R MacKenzie
- the Department of Pathology, Baylor College of Medicine, Houston, Texas 77030
| | - R Blake Hill
- the Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, and
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17
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Clairfeuille T, Norwood SJ, Qi X, Teasdale RD, Collins BM. Structure and Membrane Binding Properties of the Endosomal Tetratricopeptide Repeat (TPR) Domain-containing Sorting Nexins SNX20 and SNX21. J Biol Chem 2015; 290:14504-17. [PMID: 25882846 DOI: 10.1074/jbc.m115.650598] [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: 03/16/2015] [Indexed: 01/08/2023] Open
Abstract
Sorting nexins (SNX) orchestrate membrane trafficking and signaling events required for the proper distribution of proteins within the endosomal network. Their phox homology (PX) domain acts as a phosphoinositide (PI) recognition module that targets them to specific endocytic membrane domains. The modularity of SNX proteins confers a wide variety of functions from signaling to membrane deformation and cargo binding, and many SNXs are crucial modulators of endosome dynamics and are involved in a myriad of physiological and pathological processes such as neurodegenerative diseases, cancer, and inflammation. Here, we have studied the poorly characterized SNX20 and its paralogue SNX21, which contain an N-terminal PX domain and a C-terminal PX-associated B (PXB) domain of unknown function. The two proteins share similar PI-binding properties and are recruited to early endosomal compartments by their PX domain. The crystal structure of the SNX21 PXB domain reveals a tetratricopeptide repeat (TPR)-fold, a module that typically binds short peptide motifs, with three TPR α-helical repeats. However, the C-terminal capping helix adopts a highly unusual and potentially self-inhibitory topology. SAXS solution structures of SNX20 and SNX21 show that these proteins adopt a compact globular architecture, and membrane interaction analyses indicate the presence of overlapping PI-binding sites that may regulate their intracellular localization. This study provides the first structural analysis of this poorly characterized subfamily of SNX proteins, highlighting a likely role as endosome-associated scaffolds.
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Affiliation(s)
- Thomas Clairfeuille
- From the Institute for Molecular Bioscience, University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Suzanne J Norwood
- From the Institute for Molecular Bioscience, University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Xiaying Qi
- From the Institute for Molecular Bioscience, University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Rohan D Teasdale
- From the Institute for Molecular Bioscience, University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Brett M Collins
- From the Institute for Molecular Bioscience, University of Queensland, St. Lucia, Queensland 4072, Australia
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18
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Yamano K, Fogel AI, Wang C, van der Bliek AM, Youle RJ. Mitochondrial Rab GAPs govern autophagosome biogenesis during mitophagy. eLife 2014; 3:e01612. [PMID: 24569479 PMCID: PMC3930140 DOI: 10.7554/elife.01612] [Citation(s) in RCA: 218] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Damaged mitochondria can be selectively eliminated by mitophagy. Although two gene products mutated in Parkinson’s disease, PINK1, and Parkin have been found to play a central role in triggering mitophagy in mammals, how the pre-autophagosomal isolation membrane selectively and accurately engulfs damaged mitochondria remains unclear. In this study, we demonstrate that TBC1D15, a mitochondrial Rab GTPase-activating protein (Rab-GAP), governs autophagosome biogenesis and morphology downstream of Parkin activation. To constrain autophagosome morphogenesis to that of the cargo, TBC1D15 inhibits Rab7 activity and associates with both the mitochondria through binding Fis1 and the isolation membrane through the interactions with LC3/GABARAP family members. Another TBC family member TBC1D17, also participates in mitophagy and forms homodimers and heterodimers with TBC1D15. These results demonstrate that TBC1D15 and TBC1D17 mediate proper autophagic encapsulation of mitochondria by regulating Rab7 activity at the interface between mitochondria and isolation membranes. DOI:http://dx.doi.org/10.7554/eLife.01612.001 Parkinson disease is a common degenerative brain disorder that causes tremors, muscle stiffening, and slowing down of movement. Scientists believe that these symptoms are caused by a progressive loss of brain cells called dopaminergic neurons, which help regulate movement. Most cases have no obvious genetic cause, but around 15% of people with the disease have a close relative who also has the disease, and mutations in the genes encoding two proteins—PINK1 and Parkin—have been identified as prime suspects in familial Parkinson disease. These proteins help to eliminate damaged mitochondria from cells. In addition to producing the energy that cells need to function, mitochondria also help to trigger cell death. Pesticides and other chemicals linked to non-familial cases of Parkinson disease also damage mitochondria. Taken together, this evidence suggests that the accumulation of damaged mitochondria may contribute to the excessive loss of dopaminergic neurons that is seen in both forms of the disease. Yamano et al. provide new details on the ways that autophagosomes—structures that help cells to recycle nutrients and remove debris—destroy mitochondria. Previous studies have shown that when a mitochondrion is damaged, PINK1 sends a signal to Parkin, which then helps to recruit the proteins that are needed to form an autophagosome around the damaged mitochondrion. However, the identity of the proteins that guide the formation of the autophagosome remained a mystery. Yamano et al. have now identified two of these proteins and helped to explain their specific roles in the assembly of autophagosomes. The two proteins, which are called TBC1D15 and TBC1D17, are both GAP proteins, which are well known for their role in deactivating enzymes called RAB GTPases. Yamano et al. show that TBC1D15 binds to the damaged mitochondrion and also to the autophagosome as it grows around the mitochondrion. TBC1D15 also inhibits the action of an enzyme called Rab7 to prevent excessive growth of the autophagosome. TBC1D17 has a similar role. The work of Yamano et al. indicates that Parkin activates Rab7, perhaps by placing chains of a protein called ubiquitin on mitochondria, which would mean that an unexpected new step in this pathway remains to be discovered. Understanding how Parkin activates Rab7 could help identify new targets for drugs that might treat Parkinson disease. DOI:http://dx.doi.org/10.7554/eLife.01612.002
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Affiliation(s)
- Koji Yamano
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
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19
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Cooper KF, Khakhina S, Kim SK, Strich R. Stress-induced nuclear-to-cytoplasmic translocation of cyclin C promotes mitochondrial fission in yeast. Dev Cell 2014; 28:161-73. [PMID: 24439911 DOI: 10.1016/j.devcel.2013.12.009] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 11/08/2013] [Accepted: 12/16/2013] [Indexed: 01/01/2023]
Abstract
Mitochondrial morphology is maintained by the opposing activities of dynamin-based fission and fusion machines. In response to stress, this balance is dramatically shifted toward fission. This study reveals that the yeast transcriptional repressor cyclin C is both necessary and sufficient for stress-induced hyperfission. In response to oxidative stress, cyclin C translocates from the nucleus to the cytoplasm, where it is destroyed. Prior to its destruction, cyclin C both genetically and physically interacts with Mdv1p, an adaptor that links the GTPase Dnm1p to the mitochondrial receptor Fis1p. Cyclin C is required for stress-induced Mdv1p mitochondrial recruitment and the efficient formation of functional Dnm1p filaments. Finally, coimmunoprecipitation studies and fluorescence microscopy revealed an elevated association between Mdv1p and Dnm1p in stressed cells that is dependent on cyclin C. This study provides a mechanism by which stress-induced gene induction and mitochondrial fission are coordinated through translocation of cyclin C.
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Affiliation(s)
- Katrina F Cooper
- Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Stratford, NJ 08084, USA
| | - Svetlana Khakhina
- Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Stratford, NJ 08084, USA
| | - Stephen K Kim
- Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Stratford, NJ 08084, USA
| | - Randy Strich
- Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Stratford, NJ 08084, USA.
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20
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Disatnik MH, Ferreira JCB, Campos JC, Gomes KS, Dourado PMM, Qi X, Mochly-Rosen D. Acute inhibition of excessive mitochondrial fission after myocardial infarction prevents long-term cardiac dysfunction. J Am Heart Assoc 2013; 2:e000461. [PMID: 24103571 PMCID: PMC3835263 DOI: 10.1161/jaha.113.000461] [Citation(s) in RCA: 240] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Background Ischemia and reperfusion (IR) injury remains a major cause of morbidity and mortality and multiple molecular and cellular pathways have been implicated in this injury. We determined whether acute inhibition of excessive mitochondrial fission at the onset of reperfusion improves mitochondrial dysfunction and cardiac contractility postmyocardial infarction in rats. Methods and Results We used a selective inhibitor of the fission machinery, P110, which we have recently designed. P110 treatment inhibited the interaction of fission proteins Fis1/Drp1, decreased mitochondrial fission, and improved bioenergetics in three different rat models of IR, including primary cardiomyocytes, ex vivo heart model, and an in vivo myocardial infarction model. Drp1 transiently bound to the mitochondria following IR injury and P110 treatment blocked this Drp1 mitochondrial association. Compared with control treatment, P110 (1 μmol/L) decreased infarct size by 28±2% and increased adenosine triphosphate levels by 70+1% after IR relative to control IR in the ex vivo model. Intraperitoneal injection of P110 (0.5 mg/kg) at the onset of reperfusion in an in vivo model resulted in improved mitochondrial oxygen consumption by 68% when measured 3 weeks after ischemic injury, improved cardiac fractional shortening by 35%, reduced mitochondrial H2O2 uncoupling state by 70%, and improved overall mitochondrial functions. Conclusions Together, we show that excessive mitochondrial fission at reperfusion contributes to long‐term cardiac dysfunction in rats and that acute inhibition of excessive mitochondrial fission at the onset of reperfusion is sufficient to result in long‐term benefits as evidenced by inhibiting cardiac dysfunction 3 weeks after acute myocardial infarction.
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Affiliation(s)
- Marie-Hélène Disatnik
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, 94305, CA
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21
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Zhan M, Brooks C, Liu F, Sun L, Dong Z. Mitochondrial dynamics: regulatory mechanisms and emerging role in renal pathophysiology. Kidney Int 2013; 83:568-81. [PMID: 23325082 PMCID: PMC3612360 DOI: 10.1038/ki.2012.441] [Citation(s) in RCA: 261] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mitochondria are a class of dynamic organelles that constantly undergo fission and fusion. Mitochondrial dynamics is governed by a complex molecular machinery and finely tuned by regulatory proteins. During cell injury or stress, the dynamics is shifted to fission, resulting in mitochondrial fragmentation, which contributes to mitochondrial damage and consequent cell injury and death. Emerging evidence has suggested a role of mitochondrial fragmentation in the pathogenesis of renal diseases including acute kidney injury and diabetic nephropathy. A better understanding of the regulation of mitochondrial dynamics and its pathogenic changes may unveil novel therapeutic strategies.
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Affiliation(s)
- Ming Zhan
- Department of Nephrology, Second Xiangya Hospital, Central South University, Changsha, China
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22
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Qi X, Qvit N, Su YC, Mochly-Rosen D. A novel Drp1 inhibitor diminishes aberrant mitochondrial fission and neurotoxicity. J Cell Sci 2012; 126:789-802. [PMID: 23239023 DOI: 10.1242/jcs.114439] [Citation(s) in RCA: 285] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Excessive mitochondrial fission is associated with the pathology of a number of neurodegenerative diseases. Therefore, inhibitors of aberrant mitochondrial fission could provide important research tools in addition to potential leads for drug development. Using a rational approach, we designed a novel and selective peptide inhibitor, P110, of excessive mitochondrial fission. P110 inhibits Drp1 enzyme activity and blocks Drp1/Fis1 interaction in vitro and in cultured neurons, whereas it has no effect on the interaction between Drp1 and other mitochondrial adaptors, as demonstrated by co-immunoprecipitation. Furthermore, using a model of Parkinson's disease (PD) in culture, we demonstrated that P110 is neuroprotective by inhibiting mitochondrial fragmentation and reactive oxygen species (ROS) production and subsequently improving mitochondrial membrane potential and mitochondrial integrity. P110 increased neuronal cell viability by reducing apoptosis and autophagic cell death, and reduced neurite loss of primary dopaminergic neurons in this PD cell culture model. We also found that P110 treatment appears to have minimal effects on mitochondrial fission and cell viability under basal conditions. Finally, P110 required the presence of Drp1 to inhibit mitochondrial fission under oxidative stress conditions. Taken together, our findings suggest that P110, as a selective peptide inhibitor of Drp1, might be useful for the treatment of diseases in which excessive mitochondrial fission and mitochondrial dysfunction occur.
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Affiliation(s)
- Xin Qi
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Case Western Reserve University School of Medicine Cleveland, OH 44106 Cleveland, OH 44106 USA.
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23
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Zhao J, Lendahl U, Nistér M. Regulation of mitochondrial dynamics: convergences and divergences between yeast and vertebrates. Cell Mol Life Sci 2012; 70:951-76. [PMID: 22806564 PMCID: PMC3578726 DOI: 10.1007/s00018-012-1066-6] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 06/18/2012] [Accepted: 06/19/2012] [Indexed: 12/20/2022]
Abstract
In eukaryotic cells, the shape of mitochondria can be tuned to various physiological conditions by a balance of fusion and fission processes termed mitochondrial dynamics. Mitochondrial dynamics controls not only the morphology but also the function of mitochondria, and therefore is crucial in many aspects of a cell’s life. Consequently, dysfunction of mitochondrial dynamics has been implicated in a variety of human diseases including cancer. Several proteins important for mitochondrial fusion and fission have been discovered over the past decade. However, there is emerging evidence that there are as yet unidentified proteins important for these processes and that the fusion/fission machinery is not completely conserved between yeast and vertebrates. The recent characterization of several mammalian proteins important for the process that were not conserved in yeast, may indicate that the molecular mechanisms regulating and controlling the morphology and function of mitochondria are more elaborate and complex in vertebrates. This difference could possibly be a consequence of different needs in the different cell types of multicellular organisms. Here, we review recent advances in the field of mitochondrial dynamics. We highlight and discuss the mechanisms regulating recruitment of cytosolic Drp1 to the mitochondrial outer membrane by Fis1, Mff, and MIEF1 in mammals and the divergences in regulation of mitochondrial dynamics between yeast and vertebrates.
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Affiliation(s)
- Jian Zhao
- Department of Oncology-Pathology, Karolinska Institutet, CCK R8:05, Karolinska University Hospital Solna, 171 76, Stockholm, Sweden,
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24
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Lees JPB, Manlandro CM, Picton LK, Tan AZE, Casares S, Flanagan JM, Fleming KG, Hill RB. A designed point mutant in Fis1 disrupts dimerization and mitochondrial fission. J Mol Biol 2012; 423:143-58. [PMID: 22789569 DOI: 10.1016/j.jmb.2012.06.042] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Revised: 06/21/2012] [Accepted: 06/24/2012] [Indexed: 01/06/2023]
Abstract
Mitochondrial and peroxisomal fission are essential processes with defects resulting in cardiomyopathy and neonatal lethality. Central to organelle fission is Fis1, a monomeric tetratricopeptide repeat (TPR)-like protein whose role in assembly of the fission machinery remains obscure. Two nonfunctional, Saccharomyces cerevisiae Fis1 mutants (L80P or E78D/I85T/Y88H) were previously identified in genetic screens. Here, we find that these two variants in the cytosolic domain of Fis1 (Fis1ΔTM) are unexpectedly dimeric. A truncation variant of Fis1ΔTM that lacks an N-terminal regulatory domain is also found to be dimeric. The ability to dimerize is a property innate to the native Fis1ΔTM amino acid sequence as we find this domain is dimeric after transient exposure to elevated temperature or chemical denaturants and is kinetically trapped at room temperature. This is the first demonstration of a specific self-association in solution for the Fis1 cytoplasmic domain. We propose a three-dimensional domain-swapped model for dimerization that is validated by a designed mutation, A72P, which potently disrupts dimerization of wild-type Fis1. A72P also disrupts dimerization of nonfunctional variants, indicating a common structural basis for dimerization. The obligate monomer variant A72P, like the dimer-promoting variants, is nonfunctional in fission, consistent with a model in which Fis1 activity depends on its ability to interconvert between monomer and dimer species. These studies suggest a new functionally important manner in which TPR-containing proteins may reversibly self-associate.
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Affiliation(s)
- Jonathan P B Lees
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
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25
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Elgass K, Pakay J, Ryan MT, Palmer CS. Recent advances into the understanding of mitochondrial fission. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:150-61. [PMID: 22580041 DOI: 10.1016/j.bbamcr.2012.05.002] [Citation(s) in RCA: 188] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Revised: 04/24/2012] [Accepted: 05/02/2012] [Indexed: 12/20/2022]
Abstract
Mitochondria exist as a highly dynamic tubular network, and their morphology is governed by the delicate balance between frequent fusion and fission events, as well as by interactions with the cytoskeleton. Alterations in mitochondrial morphology are associated with changes in metabolism, cell development and cell death, whilst several human pathologies have been associated with perturbations in the cellular machinery that coordinate these processes. Mitochondrial fission also contributes to ensuring the proper distribution of mitochondria in response to the energetic requirements of the cell. The master mediator of fission is Dynamin related protein 1 (Drp1), which polymerises and constricts mitochondria to facilitate organelle division. The activity of Drp1 at the mitochondrial outer membrane is regulated through post-translational modifications and interactions with mitochondrial receptor and accessory proteins. This review will concentrate on recent advances made in delineating the mechanism of mitochondrial fission, and will highlight the importance of mitochondrial fission in health and disease. This article is part of a Special Issue entitled: Mitochondrial dynamics and physiology.
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Affiliation(s)
- Kirstin Elgass
- Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Australia
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26
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Zhang Y, Chan NC, Ngo HB, Gristick H, Chan DC. Crystal structure of mitochondrial fission complex reveals scaffolding function for mitochondrial division 1 (Mdv1) coiled coil. J Biol Chem 2012; 287:9855-9861. [PMID: 22303011 PMCID: PMC3323041 DOI: 10.1074/jbc.m111.329359] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The mitochondrial fission machinery is best understood in the yeast Saccharomyces cerevisiae, where Fis1, Mdv1, and Dnm1 are essential components. Fis1 is a mitochondrial outer membrane protein that recruits the dynamin-related GTPase Dnm1 during the fission process. This recruitment occurs via Mdv1, which binds both Fis1 and Dnm1 and therefore functions as a molecular adaptor linking the two molecules. Mdv1 has a modular structure, consisting of an N-terminal extension that binds Fis1, a central coiled coil for dimerization, and a C-terminal WD40 repeat region that binds Dnm1. We have solved the crystal structure of a dimeric Mdv1-Fis1 complex that contains both the N-terminal extension and coiled-coil regions of Mdv1. Consistent with previous studies, Mdv1 binds Fis1 through a U-shaped helix-loop-helix motif, and dimerization of the Mdv1-Fis1 complex is mediated by the antiparallel coiled coil of Mdv1. However, the complex is surprisingly compact and rigid due to two additional contacts mediated by the surface of the Mdv1 coiled coil. The coiled coil packs against both Fis1 and the second helix of the Mdv1 helix-loop-helix motif. Mutational analyses showed that these contacts are important for mitochondrial fission activity. These results indicate that, in addition to dimerization, the unusually long Mdv1 coiled coil serves a scaffolding function to stabilize the Mdv1-Fis1 complex.
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Affiliation(s)
- Yan Zhang
- Division of Biology, California Institute of Technology, Pasadena, California 91125
| | - Nickie C Chan
- Division of Biology, California Institute of Technology, Pasadena, California 91125; Howard Hughes Medical Institute, California Institute of Technology, Pasadena, California 91125
| | - Huu B Ngo
- Division of Biology, California Institute of Technology, Pasadena, California 91125
| | - Harry Gristick
- Division of Biology, California Institute of Technology, Pasadena, California 91125
| | - David C Chan
- Division of Biology, California Institute of Technology, Pasadena, California 91125; Howard Hughes Medical Institute, California Institute of Technology, Pasadena, California 91125.
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Tooley JE, Khangulov V, Lees JPB, Schlessman JL, Bewley MC, Heroux A, Bosch J, Hill RB. The 1.75 Å resolution structure of fission protein Fis1 from Saccharomyces cerevisiae reveals elusive interactions of the autoinhibitory domain. Acta Crystallogr Sect F Struct Biol Cryst Commun 2011; 67:1310-5. [PMID: 22102223 DOI: 10.1107/s1744309111029368] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Accepted: 07/20/2011] [Indexed: 11/10/2022]
Abstract
Fis1 mediates mitochondrial and peroxisomal fission. It is tail-anchored to these organelles by a transmembrane domain, exposing a soluble cytoplasmic domain. Previous studies suggested that Fis1 is autoinhibited by its N-terminal region. Here, a 1.75 Å resolution crystal structure of the Fis1 cytoplasmic domain from Saccharomyces cerevisiae is reported which adopts a tetratricopeptide-repeat fold. It is observed that this fold creates a concave surface important for fission, but is sterically occluded by its N-terminal region. Thus, this structure provides a physical basis for autoinhibition and allows a detailed examination of the interactions that stabilize the inhibited state of this molecule.
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Affiliation(s)
- James E Tooley
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
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28
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Wells RC, Hill RB. The cytosolic domain of Fis1 binds and reversibly clusters lipid vesicles. PLoS One 2011; 6:e21384. [PMID: 21738650 PMCID: PMC3125187 DOI: 10.1371/journal.pone.0021384] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Accepted: 05/27/2011] [Indexed: 11/18/2022] Open
Abstract
Every lipid membrane fission event involves the association of two apposing bilayers, mediated by proteins that can promote membrane curvature, fusion and fission. We tested the hypothesis that Fis1, a tail-anchored protein involved in mitochondrial and peroxisomal fission, promotes changes in membrane structure. We found that the cytosolic domain of Fis1 alone binds lipid vesicles, which is enhanced upon protonation and increasing concentrations of anionic phospholipids. Fluorescence and circular dichroism data indicate that the cytosolic domain undergoes a membrane-induced conformational change that buries two tryptophan side chains upon membrane binding. Light scattering and electron microscopy data show that membrane binding promotes lipid vesicle clustering. Remarkably, this vesicle clustering is reversible and vesicles largely retain their original shape and size. This raises the possibility that the Fis1 cytosolic domain might act in membrane fission by promoting a reversible membrane association, a necessary step in membrane fission.
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Affiliation(s)
- Robert C. Wells
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - R. Blake Hill
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland, United States of America
- * E-mail:
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29
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Kageyama Y, Zhang Z, Sesaki H. Mitochondrial division: molecular machinery and physiological functions. Curr Opin Cell Biol 2011; 23:427-34. [PMID: 21565481 DOI: 10.1016/j.ceb.2011.04.009] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Revised: 03/10/2011] [Accepted: 04/18/2011] [Indexed: 01/12/2023]
Abstract
Mitochondrial division has emerged as a key mechanism for this essential organelle to maintain its structural integrity, intracellular distribution, and functional competence. An evolutionarily conserved dynamin-related GTPase, Dnm1p/Drp1, interacts with other proteins to form the core machinery involved in mitochondrial division. We summarize recent progress in understanding how the division machinery assembles onto mitochondria and how mitochondrial division contributes to cellular physiology and human diseases.
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Affiliation(s)
- Yusuke Kageyama
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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30
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Abstract
Mitochondria are highly dynamic organelles and undergo continuous fission and fusion events in physiological situations. It was observed that mitochondrial morphology and number are changed in living cells during cellular differentiation, development, and under pathological conditions including muscle dystrophy, cardiomyopathy, and cancer. Defined sets of proteins are known to mediate mitochondrial fission and fusion and to constitute regulatory components controlling mitochondrial dynamics. In the present study, we first investigated mitochondrial dynamics during the cell cycle progression, and found that mitochondria exist as filamentous network structures throughout the cell cycle progression, changing their morphology, distribution, and abundance. In addition, we found that a mouse homolog of human DNA polymerase delta interacting protein 38, referred to as Mitogenin I, and mitochondrial single-stranded DNA-binding protein (mtSSB), identified as upregulated genes in the heart of mice with juvenile visceral steatosis, play a role in the regulation of mitochondrial morphology.
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Affiliation(s)
- Midori Suenaga
- Department of Medical Pharmacology, Faculty of Pharmaceutical Science, Tokushima Bunri University, Tokushima, Japan.
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31
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Landes T, Martinou JC. Mitochondrial outer membrane permeabilization during apoptosis: the role of mitochondrial fission. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:540-5. [PMID: 21277336 DOI: 10.1016/j.bbamcr.2011.01.021] [Citation(s) in RCA: 109] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 01/13/2011] [Accepted: 01/13/2011] [Indexed: 01/25/2023]
Abstract
Mitochondria continually fuse and divide to yield a dynamic interconnected network throughout the cell. During apoptosis, concomitantly with permeabilization of the mitochondrial outer membrane (MOMP) and cytochrome c release, mitochondria undergo massive fission. This results in the formation of small, round organelles that tend to aggregate around the nucleus. Under some circumstances, preceding their fission, mitochondria tend to elongate and to hyperfuse, a process that is interpreted as a cell defense mechanism. Since many years, there is a controversy surrounding the physiological relevance of mitochondrial fragmentation in apoptosis. In this review, we present recent advances in this field, describe the mechanisms that underlie this process, and discuss how they could cooperate with Bax to trigger MOMP and cytochrome c release. This article is part of a Special Issue entitled Mitochondria: the deadly organelle.
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Affiliation(s)
- Thomas Landes
- Department of Cell Biology, University of Geneva, Sciences III, 30 quai Ernest Ansermet, 1211 Geneva 4, Switzerland
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Otera H, Wang C, Cleland MM, Setoguchi K, Yokota S, Youle RJ, Mihara K. Mff is an essential factor for mitochondrial recruitment of Drp1 during mitochondrial fission in mammalian cells. ACTA ACUST UNITED AC 2011; 191:1141-58. [PMID: 21149567 PMCID: PMC3002033 DOI: 10.1083/jcb.201007152] [Citation(s) in RCA: 766] [Impact Index Per Article: 58.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The cytoplasmic dynamin-related guanosine triphosphatase Drp1 is recruited to mitochondria and mediates mitochondrial fission. Although the mitochondrial outer membrane (MOM) protein Fis1 is thought to be a Drp1 receptor, this has not been confirmed. To analyze the mechanism of Drp1 recruitment, we manipulated the expression of mitochondrial fission and fusion proteins and demonstrated that (a) mitochondrial fission factor (Mff) knockdown released the Drp1 foci from the MOM accompanied by network extension, whereas Mff overexpression stimulated mitochondrial recruitment of Drp1 accompanied by mitochondrial fission; (b) Mff-dependent mitochondrial fission proceeded independent of Fis1; (c) a Mff mutant with the plasma membrane-targeted CAAX motif directed Drp1 to the target membrane; (d) Mff and Drp1 physically interacted in vitro and in vivo; (e) exogenous stimuli-induced mitochondrial fission and apoptosis were compromised by knockdown of Drp1 and Mff but not Fis1; and (f) conditional knockout of Fis1 in colon carcinoma cells revealed that it is dispensable for mitochondrial fission. Thus, Mff functions as an essential factor in mitochondrial recruitment of Drp1.
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Affiliation(s)
- Hidenori Otera
- Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, Fukuoka 812-8582, Japan
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33
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Koirala S, Bui HT, Schubert HL, Eckert DM, Hill CP, Kay MS, Shaw JM. Molecular architecture of a dynamin adaptor: implications for assembly of mitochondrial fission complexes. J Cell Biol 2010; 191:1127-39. [PMID: 21149566 PMCID: PMC3002026 DOI: 10.1083/jcb.201005046] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Accepted: 11/08/2010] [Indexed: 01/07/2023] Open
Abstract
Recruitment and assembly of some dynamin-related guanosine triphosphatases depends on adaptor proteins restricted to distinct cellular membranes. The yeast Mdv1 adaptor localizes to mitochondria by binding to the membrane protein Fis1. Subsequent Mdv1 binding to the mitochondrial dynamin Dnm1 stimulates Dnm1 assembly into spirals, which encircle and divide the mitochondrial compartment. In this study, we report that dimeric Mdv1 is joined at its center by a 92-Å antiparallel coiled coil (CC). Modeling of the Fis1-Mdv1 complex using available crystal structures suggests that the Mdv1 CC lies parallel to the bilayer with N termini at opposite ends bound to Fis1 and C-terminal β-propeller domains (Dnm1-binding sites) extending into the cytoplasm. A CC length of appropriate length and sequence is necessary for optimal Mdv1 interaction with Fis1 and Dnm1 and is important for proper Dnm1 assembly before membrane scission. Our results provide a framework for understanding how adaptors act as scaffolds to orient and stabilize the assembly of dynamins on membranes.
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Affiliation(s)
- Sajjan Koirala
- Department of Biochemistry, University of Utah, Salt Lake City, UT 84112, USA
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34
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Lackner LL, Nunnari J. Small molecule inhibitors of mitochondrial division: tools that translate basic biological research into medicine. ACTA ACUST UNITED AC 2010; 17:578-83. [PMID: 20609407 DOI: 10.1016/j.chembiol.2010.05.016] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Revised: 05/07/2010] [Accepted: 05/28/2010] [Indexed: 12/01/2022]
Abstract
Mitochondria do not exist as discrete static entities; rather, mitochondria form a network that continuously moves, divides, and fuses. The structure of this dynamic network is in part maintained by a balance of division and fusion events (Hoppins et al., 2007). The ratio of division to fusion events that defines a proper balance is not universal but varies with developmental stage, cell type, and biological circumstances. This is evident throughout the cell cycle in higher eukaryotes, where mitochondria elongate during the G1/S transition and fragment at the onset of mitosis, and when mitochondria fragment in response to certain cellular stimuli, such as increases in cytosolic calcium levels (Breckenridge et al., 2003; Cereghetti et al., 2008; Han et al., 2008; Mitra et al., 2009; Taguchi et al., 2007). The functional state and distribution of mitochondria are clearly influenced by its steady-state structure. When the normal balance of division and fusion is disrupted as a consequence of the inappropriate stimulation or inhibition of either process, problems arise at the cellular level that compromises the well-being of the organism as a whole. This is evident by the ever-increasing number of diseases in which abnormal mitochondrial dynamics have been etiologically implicated. In this context, the mitochondrial division and fusion machines are valuable and interesting targets of small molecule effectors, as inhibition or activation of these processes may be able to restore the proper dynamic balance and function. A small molecule inhibitor of mitochondrial division, mdivi-1, has already been identified and characterized (Cassidy-Stone et al., 2008). This inhibitor has provided valuable insight into the mechanism of mitochondrial division and has shown great therapeutic promise in a wide array of disease models. This review will focus on small molecule effectors of mitochondrial division, discussing their value in basic biological research as well as their therapeutic potential.
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Affiliation(s)
- Laura L Lackner
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
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35
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Mitochondrial fission and fusion and their roles in the heart. J Mol Med (Berl) 2010; 88:971-9. [PMID: 20835916 DOI: 10.1007/s00109-010-0674-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 08/11/2010] [Accepted: 08/13/2010] [Indexed: 12/23/2022]
Abstract
Mitochondria are dynamic organelles that usually exist in extensive and interconnected networks that undergo constant remodeling through fission and fusion. These processes are governed by distinct sets of proteins whose mechanism and regulation we are only beginning to fully understand. Early studies on mitochondrial dynamics were performed in yeast and simple mammalian cell culture models that allowed easy visualization of these intricate networks. Equipped with this core understanding, the field is now expanding into more complex systems. Cardiac cells are a particularly interesting example because they have unique energetic and spatial demands that make the study of their mitochondria both challenging and potentially very fruitful. This review will provide an overview of mitochondrial fission and fusion as well as recent developments in the understanding of these processes in the heart.
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36
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Jourdain I, Gachet Y, Hyams JS. The dynamin related protein Dnm1 fragments mitochondria in a microtubule-dependent manner during the fission yeast cell cycle. ACTA ACUST UNITED AC 2009; 66:509-23. [PMID: 19373772 DOI: 10.1002/cm.20351] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Mitochondria are dynamic organelles that undergo cycles of fission and fusion. In the fission yeast, Schizosaccharomyces pombe, mitochondria align with microtubules and mitochondrial integrity is dependent upon an intact microtubule cytoskeleton. Here we show that mitochondria re-organize during the cell cycle and that this process is both dynamin- and microtubule-dependent. Microtubule depolymerization results in mitochondrial fragmentation but only when the dynamin-related protein Dnm1 is present. Mitochondrial fusion is, on the other hand, microtubule-independent. dnm1Delta cells, besides showing extensively fused mitochondria, are specifically resistant to anti-microtubule drugs. Dnm1-YFP localizes to foci at sites of mitochondrial severing which occupy the interface between adjacent nucleoids, suggesting the existence of defined mitochondrial "territories," each of which contains a nucleoid. Such territories are lost in dnm1Delta in which nucleoids become aggregated. Mitochondrial ends exhibit motile behavior, extending towards and retracting from the cell poles, independently of the cytoskeleton. We conclude that: (a) mitochondria are organized by microtubules in fission yeast but are not moved by them; (b) Dnm1 mediates mitochondrial fission during interphasic growth and at cell division; (c) the interaction between microtubules and mitochondria, either directly or indirectly via Dnm1, not only modifies the disposition of mitochondria it also modifies the behavior of microtubules. Cell Motil. Cytoskeleton 2009. (c) 2009 Wiley-Liss, Inc.
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Affiliation(s)
- Isabelle Jourdain
- Institute of Molecular Biosciences, Massey University, Private Bag 11 222, Palmerston North, New Zealand
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37
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Picton LK, Casares S, Monahan AC, Majumdar A, Hill RB. Evidence for conformational heterogeneity of fission protein Fis1 from Saccharomyces cerevisiae. Biochemistry 2009; 48:6598-609. [PMID: 19522466 DOI: 10.1021/bi802221h] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Fission 1 (Fis1) is an evolutionarily conserved, type II integral membrane protein implicated in maintaining the proper morphology of mitochondria and peroxisomes. A concave surface on the cytosolic domain of Fis1 from Saccharomyces cerevisiae is implicated in binding other fission proteins, yet structural studies reveal that this surface is sterically occluded by its N-terminal arm. Here we address the question of whether the N-terminal arm of yeast Fis1 exists in a dynamic equilibrium that would allow access to this functionally important surface. NMR measurements sensitive to dynamics occurring on a wide range of time scales (picoseconds to minutes) were used to assess whether the Fis1 arm is dynamic. Hydrogen-deuterium exchange experiments revealed that the Fis1 arm, alpha-helix 6, and proximal loops were not protected from solvent exchange, consistent with motions on the second to minute time scale. An engineered cysteine, I85C, located on the concave surface that lies underneath the Fis1 arm, was readily modified by a fluorescent probe, revealing more solvent accessibility of this position than would be predicted from the structure. Chemical denaturation, NMR chemical shift perturbation, and residual dipolar coupling experiments support the idea that the dynamic equilibrium can be shifted on the basis of changing pH and temperature, with the changes primarily localizing to the Fis1 arm and proximal regions. The data as a whole are consistent with the Fis1 arm adopting a primarily "closed" conformational state able to undergo dynamic excursions that reveal the concave surface and therefore may be important for binding other fission factors and for Fis1 function.
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Affiliation(s)
- Lora K Picton
- Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218, USA
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38
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Lackner LL, Nunnari JM. The molecular mechanism and cellular functions of mitochondrial division. Biochim Biophys Acta Mol Basis Dis 2008; 1792:1138-44. [PMID: 19100831 DOI: 10.1016/j.bbadis.2008.11.011] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2008] [Revised: 11/19/2008] [Accepted: 11/20/2008] [Indexed: 11/27/2022]
Abstract
Mitochondria are highly dynamic organelles that continuously divide and fuse. These dynamic processes regulate the size, shape, and distribution of the mitochondrial network. In addition, mitochondrial division and fusion play critical roles in cell physiology. This review will focus on the dynamic process of mitochondrial division, which is highly conserved from yeast to humans. We will discuss what is known about how the essential components of the division machinery function to mediate mitochondrial division and then focus on proteins that have been implicated in division but whose functions remain unclear. We will then briefly discuss the cellular functions of mitochondrial division and the problems that arise when division is disrupted.
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Affiliation(s)
- Laura L Lackner
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA
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39
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Delille HK, Schrader M. Targeting of hFis1 to peroxisomes is mediated by Pex19p. J Biol Chem 2008; 283:31107-15. [PMID: 18782765 PMCID: PMC2662177 DOI: 10.1074/jbc.m803332200] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2008] [Revised: 09/03/2008] [Indexed: 11/06/2022] Open
Abstract
The processes of peroxisome formation and proliferation are still a matter of debate. We have previously shown that peroxisomes share some components of their division machinery with mitochondria. hFis1, a tail-anchored membrane protein, regulates the membrane fission of both organelles by DLP1/Drp1 recruitment, but nothing is known about the mechanisms of the dual targeting of hFis1. Here we demonstrate for the first time that peroxisomal targeting of hFis1 depends on Pex19p, a peroxisomal membrane protein import factor. hFis1/Pex19p binding was demonstrated by expression and co-immunoprecipitation studies. Using mutated versions of hFis1 an essential binding region for Pex19p was located within the last 26 C-terminal amino acids of hFis1, which are required for proper targeting to both mitochondria and peroxisomes. The basic amino acids in the very C terminus are not essential for Pex19p binding and peroxisomal targeting, but are instead required for mitochondrial targeting. Silencing of Pex19p by small interference RNA reduced the targeting of hFis1 to peroxisomes, but not to mitochondria. In contrast, overexpression of Pex19p alone was not sufficient to shift the targeting of hFis1 to peroxisomes. Our findings indicate that targeting of hFis1 to peroxisomes and mitochondria are independent events and support a direct, Pex19p-dependent targeting of peroxisomal tail-anchored proteins.
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Affiliation(s)
- Hannah K Delille
- Department of Biology, University of Aveiro, Campus Universitário de Santiago, Aveiro 3810-193, Portugal
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40
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Serasinghe MN, Yoon Y. The mitochondrial outer membrane protein hFis1 regulates mitochondrial morphology and fission through self-interaction. Exp Cell Res 2008; 314:3494-507. [PMID: 18845145 DOI: 10.1016/j.yexcr.2008.09.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Revised: 09/03/2008] [Accepted: 09/04/2008] [Indexed: 11/16/2022]
Abstract
Mitochondrial fission in mammals is mediated by at least two proteins, DLP1/Drp1 and hFis1. DLP1 mediates the scission of mitochondrial membranes through GTP hydrolysis, and hFis1 is a putative DLP1 receptor anchored at the mitochondrial outer membrane by a C-terminal single transmembrane domain. The cytosolic domain of hFis1 contains six alpha-helices (alpha1-alpha6) out of which alpha2-alpha5 form two tetratricopeptide repeat (TPR) folds. In this study, by using chimeric constructs, we demonstrated that the cytosolic domain contains the necessary information for hFis1 function during mitochondrial fission. By using transient expression of different mutant forms of the hFis1 protein, we found that hFis1 self-interaction plays an important role in mitochondrial fission. Our results show that deletion of the alpha1 helix greatly increased the formation of dimeric and oligomeric forms of hFis1, indicating that alpha1 helix functions as a negative regulator of the hFis1 self-interaction. Further mutational approaches revealed that a tyrosine residue in the alpha5 helix and the linker between alpha3 and alpha4 helices participate in hFis1 oligomerization. Mutations causing oligomerization defect greatly reduced the ability to induce not only mitochondrial fragmentation by full-length hFis1 but also the formation of swollen ball-shaped mitochondria caused by alpha1-deleted hFis1. Our data suggest that oligomerization of hFis1 in the mitochondrial outer membrane plays a role in mitochondrial fission, potentially through participating in fission factor recruitment.
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Affiliation(s)
- Madhavika N Serasinghe
- Department of Biochemistry and Biophysics, Mitochondrial Research and Innovation Group, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
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41
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Structural basis for recruitment of mitochondrial fission complexes by Fis1. Proc Natl Acad Sci U S A 2007; 104:18526-30. [PMID: 17998537 DOI: 10.1073/pnas.0706441104] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mitochondrial fission controls mitochondrial shape and physiology, including mitochondrial remodeling in apoptosis. During assembly of the yeast mitochondrial fission complex, the outer membrane protein Fis1 recruits the dynamin-related GTPase Dnm1 to mitochondria. Fis1 contains a tetratricopeptide repeat (TPR) domain and interacts with Dnm1 via the molecular adaptors Mdv1 and Caf4. By using crystallographic analysis of adaptor-Fis1 complexes, we show that these adaptors use two helices to bind to both the concave and convex surfaces of the Fis1 TPR domain. Fis1 therefore contains two interaction interfaces, a binding mode that, to our knowledge, has not been observed previously for TPR domains. Genetic and biochemical studies indicate that both binding interfaces are important for binding of Mdv1 and Caf4 to Fis1 and for mitochondrial fission activity in vivo. Our results reveal how Fis1 recruits the mitochondrial fission complex and will facilitate efforts to manipulate mitochondrial fission.
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42
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Schrader M, Yoon Y. Mitochondria and peroxisomes: Are the ‘Big Brother’ and the ‘Little Sister’ closer than assumed? Bioessays 2007; 29:1105-14. [DOI: 10.1002/bies.20659] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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43
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Wells RC, Picton LK, Williams SCP, Tan FJ, Hill RB. Direct binding of the dynamin-like GTPase, Dnm1, to mitochondrial dynamics protein Fis1 is negatively regulated by the Fis1 N-terminal arm. J Biol Chem 2007; 282:33769-33775. [PMID: 17884824 PMCID: PMC3046406 DOI: 10.1074/jbc.m700807200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Recruitment of a dynamin-like GTPase (Drp1/Dlp1/Dnm1) to membranes requires the mitochondrial dynamics protein Fis1. Mdv1 has been proposed to act as an adaptor between Fis1 and Dnm1 in Saccharomyces cerevisiae. We show that S. cerevisiae Fis1 binds directly to Dnm1 and to Mdv1. Two Fis1 regions have been previously implicated in Mdv1 recruitment: an N-terminal "arm" and a concave surface formed by evolutionarily conserved residues in the tetratricopeptide repeat domain. Perturbing either Fis1 region does not affect Mdv1 binding, but both regions influence Dnm1 binding. Fis1 lacking its N-terminal arm binds tightly to Dnm1, and binding is abolished by mutations to the Fis1 concave surface. The Fis1-Dnm1 interaction decreases more than 100-fold in the presence of the Fis1 arm, suggesting that the arm acts in an autoinhibitory manner to restrict access to the Dnm1 binding site on Fis1. Our data indicate that the concave surface of the Fis1 tetratricopeptide repeat-like domain is evolutionarily conserved to bind the dynamin-like GTPase Dnm1 and not Mdv1 as previously predicted.
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Affiliation(s)
- Robert C Wells
- Department of Biology, The Johns Hopkins University, Baltimore, Maryland, 21218
| | - Lora K Picton
- Department of Biology, The Johns Hopkins University, Baltimore, Maryland, 21218
| | - Sarah C P Williams
- Department of Biology, The Johns Hopkins University, Baltimore, Maryland, 21218
| | - Frederick J Tan
- Department of Biology, The Johns Hopkins University, Baltimore, Maryland, 21218
| | - R Blake Hill
- Department of Biology, The Johns Hopkins University, Baltimore, Maryland, 21218; Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218.
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44
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Abstract
Mitochondria are derived from eubacteria; however, in most eukaryotes, novel mechanisms for the propagation of this organelle and its genome have evolved. This review focuses on what is currently known about the novel molecular machines that divide and fuse mitochondria.
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Affiliation(s)
- Suzanne Hoppins
- Section of Molecular and Cellular Biology, University of California, Davis, California 95616, USA.
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45
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Tjandra N, Suzuki M, Chang SL. Refinement of protein structure against non-redundant carbonyl 13C NMR relaxation. JOURNAL OF BIOMOLECULAR NMR 2007; 38:243-53. [PMID: 17554496 DOI: 10.1007/s10858-007-9165-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2007] [Accepted: 05/11/2007] [Indexed: 05/15/2023]
Abstract
Carbonyl (13)C' relaxation is dominated by the contribution from the (13)C' chemical shift anisotropy (CSA). The relaxation rates provide useful and non-redundant structural information in addition to dynamic parameters. It is straightforward to acquire, and offers complimentary structural information to the (15)N relaxation data. Furthermore, the non-axial nature of the (13)C' CSA tensor results in a T(1)/T(2) value that depends on an additional angular variable even when the diffusion tensor of the protein molecule is axially symmetric. This dependence on an extra degree of freedom provides new geometrical information that is not available from the NH dipolar relaxation. A protocol that incorporates such structural restraints into NMR structure calculation was developed within the program Xplor-NIH. Its application was illustrated with the yeast Fis1 NMR structure. Refinement against the (13)C' T(1)/T(2) improved the overall quality of the structure, as evaluated by cross-validation against the residual dipolar coupling as well as the (15)N relaxation data. In addition, possible variations of the CSA tensor were addressed.
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Affiliation(s)
- Nico Tjandra
- Laboratory of Molecular Biophysics, National Heart, Lung, and Blood Institute, National Institutes of Health, Building 50, Room 3503, Bethesda, MD 20892, USA.
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46
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Abstract
Eukaryotic cells maintain the overall shape of their mitochondria by balancing the opposing processes of mitochondrial fusion and fission. Unbalanced fission leads to mitochondrial fragmentation, and unbalanced fusion leads to mitochondrial elongation. Moreover, these processes control not only the shape but also the function of mitochondria. Mitochondrial dynamics allows mitochondria to interact with each other; without such dynamics, the mitochondrial population consists of autonomous organelles that have impaired function. Key components of the mitochondrial fusion and fission machinery have been identified, allowing initial dissection of their mechanisms of action. These components play important roles in mitochondrial function and development as well as programmed cell death. Disruption of the fusion machinery leads to neurodegenerative disease.
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Affiliation(s)
- David C Chan
- Division of Biology, California Institute of Technology, Pasadena, California, USA.
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47
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Bhar D, Karren MA, Babst M, Shaw JM. Dimeric Dnm1-G385D Interacts with Mdv1 on Mitochondria and Can Be Stimulated to Assemble into Fission Complexes Containing Mdv1 and Fis1. J Biol Chem 2006; 281:17312-17320. [PMID: 16601120 DOI: 10.1074/jbc.m513530200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Interactions between yeast Dnm1p, Mdv1p, and Fis1p are required to form fission complexes that catalyze division of the mitochondrial compartment. During the formation of mitochondrial fission complexes, the Dnm1p GTPase self-assembles into large multimeric complexes on the outer mitochondrial membrane that are visualized as punctate structures by fluorescent labeling. Although it is clear that Fis1p.Mdv1p complexes on mitochondria are required for the initial recruitment of Dnm1p, it is not clear whether Dnm1p puncta assemble before or after this recruitment step. Here we show that the minimum oligomeric form of cytoplasmic Dnm1p is a dimer. The middle domain mutant protein Dnm1G385Dp forms dimers in vivo but fails to assemble into punctate structures. However, this dimeric mutant stably interacts with Mdv1p on the outer mitochondrial membrane, demonstrating that assembly of stable Dnm1p multimers is not required for Dnm1p-Mdv1p association or for mitochondrial recruitment of Dnm1p. Dnm1G385Dp is reported to be a terminal dimer in vitro. We describe conditions that allow assembly of Dnm1G385Dp into functional fission complexes on mitochondria in vivo. Using these conditions, we demonstrate that multimerization of Dnm1p is required to promote reorganization of Mdv1p from a uniform mitochondrial localization into punctate fission complexes. Our studies also reveal that Fis1p is present in these assembled fission complexes. Based on our results, we propose that Dnm1p dimers are initially recruited to the membrane via interaction with Mdv1p.Fis1p complexes. These dimers then assemble into multimers that subsequently promote the reorganization of Mdv1p into punctate fission complexes.
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Affiliation(s)
- Debjani Bhar
- Biochemistry Department, University of Utah School of Medicine, Salt Lake City, Utah 84112-5650
| | - Mary Anne Karren
- Biochemistry Department, University of Utah School of Medicine, Salt Lake City, Utah 84112-5650
| | - Markus Babst
- Biology Department, University of Utah, Salt Lake City, Utah 84112-0840
| | - Janet M Shaw
- Biochemistry Department, University of Utah School of Medicine, Salt Lake City, Utah 84112-5650.
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48
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Schrader M. Shared components of mitochondrial and peroxisomal division. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:531-41. [PMID: 16487606 DOI: 10.1016/j.bbamcr.2006.01.004] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2005] [Revised: 01/11/2006] [Accepted: 01/13/2006] [Indexed: 12/15/2022]
Abstract
Mitochondria and peroxisomes are ubiquitous subcellular organelles, which are highly dynamic and display large plasticity. Recent studies have led to the surprising finding that both organelles share components of their division machinery, namely the dynamin-related protein DLP1/Drp1 and hFis1, which recruits DLP1/Drp1 to the organelle membranes. This review addresses the current state of knowledge concerning the dynamics and fission of peroxisomes, especially in relation to mitochondrial morphology and division in mammalian cells.
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Affiliation(s)
- Michael Schrader
- Department of Cell Biology and Cell Pathology, University of Marburg, Robert-Koch Str. 6, 35037 Marburg, Germany.
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49
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Abstract
Mitochondria form dynamic tubular networks that continually change their shape and move throughout the cell. In eukaryotes, these organellar gymnastics are controlled by numerous pathways that preserve proper mitochondrial morphology and function. The best understood of these are the fusion and fission pathways, which rely on conserved GTPases and their binding partners to regulate organelle connectivity and copy number in healthy cells and during apoptosis. In budding yeast, mitochondrial shape is also maintained by proteins acting in the tubulation pathway. Novel proteins and pathways that control mitochondrial dynamics continue to be discovered, indicating that the mechanisms governing this organelle's behavior are more sophisticated than previously appreciated. Here we review recent advances in the field of mitochondrial dynamics and highlight the importance of these pathways to human health.
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Affiliation(s)
- Koji Okamoto
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84132-3201, USA.
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50
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Scott I, Tobin AK, Logan DC. BIGYIN, an orthologue of human and yeast FIS1 genes functions in the control of mitochondrial size and number in Arabidopsis thaliana. JOURNAL OF EXPERIMENTAL BOTANY 2006; 57:1275-80. [PMID: 16510519 DOI: 10.1093/jxb/erj096] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Reverse-genetics was used to evaluate the role of an Arabidopsis homologue of the human and yeast FIS1 genes, which are both involved in mitochondrial fission. Two independent T-DNA insertion mutants of gene At3g57090 were identified and genetically transformed to express mitochondria-targeted GFP to enable visualization of mitochondria in vivo. Plants homozygous for either of the recessive T-DNA mutant alleles, termed bigyin1-1 (bgy1-1) and bigyin1-2 (bgy1-2), displayed an abnormal mitochondrial morphology. Disruption of BIGYIN leads to a reduced number of mitochondria per cell, coupled to a large increase in the size of individual mitochondria, relative to wild-type. It is concluded that BIGYIN is an Arabidopsis FIS orthologue and is part of the Arabidopsis mitochondrial division apparatus.
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Affiliation(s)
- Iain Scott
- School of Biology, Sir Harold Mitchell Building, University of St Andrews, St Andrews, Fife KY16 9TH, UK
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