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Aneli S, Ceccatelli Berti C, Gilea AI, Birolo G, Mutti G, Pavesi A, Baruffini E, Goffrini P, Capelli C. Functional characterization of archaic-specific variants in mitonuclear genes: insights from comparative analysis in S. cerevisiae. Hum Mol Genet 2024; 33:1152-1163. [PMID: 38558123 DOI: 10.1093/hmg/ddae057] [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: 01/17/2024] [Revised: 02/29/2024] [Accepted: 03/14/2024] [Indexed: 04/04/2024] Open
Abstract
Neanderthal and Denisovan hybridisation with modern humans has generated a non-random genomic distribution of introgressed regions, the result of drift and selection dynamics. Cross-species genomic incompatibility and more efficient removal of slightly deleterious archaic variants have been proposed as selection-based processes involved in the post-hybridisation purge of archaic introgressed regions. Both scenarios require the presence of functionally different alleles across Homo species onto which selection operated differently according to which populations hosted them, but only a few of these variants have been pinpointed so far. In order to identify functionally divergent archaic variants removed in humans, we focused on mitonuclear genes, which are underrepresented in the genomic landscape of archaic humans. We searched for non-synonymous, fixed, archaic-derived variants present in mitonuclear genes, rare or absent in human populations. We then compared the functional impact of archaic and human variants in the model organism Saccharomyces cerevisiae. Notably, a variant within the mitochondrial tyrosyl-tRNA synthetase 2 (YARS2) gene exhibited a significant decrease in respiratory activity and a substantial reduction of Cox2 levels, a proxy for mitochondrial protein biosynthesis, coupled with the accumulation of the YARS2 protein precursor and a lower amount of mature enzyme. Our work suggests that this variant is associated with mitochondrial functionality impairment, thus contributing to the purging of archaic introgression in YARS2. While different molecular mechanisms may have impacted other mitonuclear genes, our approach can be extended to the functional screening of mitonuclear genetic variants present across species and populations.
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Affiliation(s)
- Serena Aneli
- Department of Public Health Sciences and Pediatrics, University of Turin, C.so Galileo Galilei 22, Turin 10126, Italy
| | - Camilla Ceccatelli Berti
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/a, Parma 43124, Italy
| | - Alexandru Ionut Gilea
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/a, Parma 43124, Italy
| | - Giovanni Birolo
- Department of Medical Sciences, University of Turin, Via Santena 5, Turin 10126, Italy
| | - Giacomo Mutti
- Barcelona Supercomputing Centre (BSC-CNS), Department of Life Sciences, Plaça Eusebi Güell, 1-3, Barcelona 08034, Spain
- Institute for Research in Biomedicine (IRB Barcelona), Department of Mechanisms of Disease, The Barcelona Institute of Science and Technology, Baldiri Reixac, 10, Barcelona 08028, Spain
| | - Angelo Pavesi
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/a, Parma 43124, Italy
| | - Enrico Baruffini
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/a, Parma 43124, Italy
| | - Paola Goffrini
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/a, Parma 43124, Italy
| | - Cristian Capelli
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/a, Parma 43124, Italy
- Department of Biology, University of Oxford, 11a Mansfield Rd, Oxford OX1 3SZ, United Kingdom
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Darden C, Donkor JE, Korolkova O, Barozai MYK, Chaudhuri M. Distinct structural motifs are necessary for targeting and import of Tim17 in Trypanosoma brucei mitochondrion. mSphere 2024; 9:e0055823. [PMID: 38193679 PMCID: PMC10871166 DOI: 10.1128/msphere.00558-23] [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: 09/22/2023] [Accepted: 11/28/2023] [Indexed: 01/10/2024] Open
Abstract
Nuclear-encoded mitochondrial proteins are correctly translocated to their proper sub-mitochondrial destination using location-specific mitochondrial targeting signals and via multi-protein import machineries (translocases) in the outer and inner mitochondrial membranes (TOM and TIMs, respectively). However, targeting signals of multi-pass Tims are less defined. Here, we report the characterization of the targeting signals of Trypanosoma brucei Tim17 (TbTim17), an essential component of the most divergent TIM complex. TbTim17 possesses a characteristic secondary structure including four predicted transmembrane (TM) domains in the center with hydrophilic N- and C-termini. After examining mitochondrial localization of various deletion and site-directed mutants of TbTim17 in T. brucei using subcellular fractionation and confocal microscopy, we located at least two internal targeting signals (ITS): (i) within TM1 (31-50 AAs) and (ii) TM4 + loop 3 (120-136 AAs). Both signals are required for proper targeting and integration of TbTim17 in the membrane. Furthermore, a positively charged residue (K122) is critical for mitochondrial localization of TbTim17. This is the first report of characterizing the ITS for a multipass inner membrane protein in a divergent eukaryote, like T. brucei.IMPORTANCEAfrican trypanosomiasis (AT) is a deadly disease in human and domestic animals, caused by the parasitic protozoan Trypanosoma brucei. Therefore, AT is not only a concern for human health but also for economic development in the vast area of sub-Saharan Africa. T. brucei possesses a single mitochondrion per cell that imports hundreds of nuclear-encoded mitochondrial proteins for its functions. T. brucei Tim17 (TbTim17), an essential component of the TbTIM17 complex, is a nuclear-encoded protein; thus, it is necessary to be imported from the cytosol to form the TbTIM17 complex. Here, we demonstrated that the internal targeting signals within the transmembrane 1 (TM1) and TM4 with loop 3, and residue K122 are required collectively for import and integration of TbTim17 in the T. brucei mitochondrion. This information could be utilized to block TbTim17 function and parasite growth.
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Affiliation(s)
- Chauncey Darden
- Department of Biochemistry, Cancer Biology, Neuroscience, and Pharmacology, Meharry Medical College, Nashville, Tennessee, USA
| | - Joseph E. Donkor
- Department of Microbiology, Immunology, and Physiology, Meharry Medical College, Nashville, Tennessee, USA
| | - Olga Korolkova
- The Consolidated Research Instrumentation, Informatics, Statistics, and Learning Integration Suite (CRISALIS), Meharry Medical College, Nashville, Tennessee, USA
| | | | - Minu Chaudhuri
- Department of Microbiology, Immunology, and Physiology, Meharry Medical College, Nashville, Tennessee, USA
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Aeschlimann S, Stettler P, Schneider A. DNA segregation in mitochondria and beyond: insights from the trypanosomal tripartite attachment complex. Trends Biochem Sci 2023; 48:1058-1070. [PMID: 37775421 DOI: 10.1016/j.tibs.2023.08.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 08/13/2023] [Accepted: 08/28/2023] [Indexed: 10/01/2023]
Abstract
The tripartite attachment complex (TAC) of the single mitochondrion of trypanosomes allows precise segregation of its single nucleoid mitochondrial genome during cytokinesis. It couples the segregation of the duplicated mitochondrial genome to the segregation of the basal bodies of the flagella. Here, we provide a model of the molecular architecture of the TAC that explains how its eight essential subunits connect the basal body, across the mitochondrial membranes, with the mitochondrial genome. We also discuss how the TAC subunits are imported into the mitochondrion and how they assemble to form a new TAC. Finally, we present a comparative analysis of the trypanosomal TAC with open and closed mitotic spindles, which reveals conserved concepts between these diverse DNA segregation systems.
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Affiliation(s)
- Salome Aeschlimann
- Department of Chemistry, Biochemistry, and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, Bern CH-3012, Switzerland
| | - Philip Stettler
- Department of Chemistry, Biochemistry, and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, Bern CH-3012, Switzerland; Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern CH-3012, Switzerland
| | - André Schneider
- Department of Chemistry, Biochemistry, and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, Bern CH-3012, Switzerland; Institute for Advanced Study (Wissenschaftskolleg) Berlin, D-14193 Berlin, Germany.
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Nieto-Panqueva F, Rubalcava-Gracia D, Hamel PP, González-Halphen D. The constraints of allotopic expression. Mitochondrion 2023; 73:30-50. [PMID: 37739243 DOI: 10.1016/j.mito.2023.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 08/28/2023] [Accepted: 09/18/2023] [Indexed: 09/24/2023]
Abstract
Allotopic expression is the functional transfer of an organellar gene to the nucleus, followed by synthesis of the gene product in the cytosol and import into the appropriate organellar sub compartment. Here, we focus on mitochondrial genes encoding OXPHOS subunits that were naturally transferred to the nucleus, and critically review experimental evidence that claim their allotopic expression. We emphasize aspects that may have been overlooked before, i.e., when modifying a mitochondrial gene for allotopic expression━besides adapting the codon usage and including sequences encoding mitochondrial targeting signals━three additional constraints should be considered: (i) the average apparent free energy of membrane insertion (μΔGapp) of the transmembrane stretches (TMS) in proteins earmarked for the inner mitochondrial membrane, (ii) the final, functional topology attained by each membrane-bound OXPHOS subunit; and (iii) the defined mechanism by which the protein translocator TIM23 sorts cytosol-synthesized precursors. The mechanistic constraints imposed by TIM23 dictate the operation of two pathways through which alpha-helices in TMS are sorted, that eventually determine the final topology of membrane proteins. We used the biological hydrophobicity scale to assign an average apparent free energy of membrane insertion (μΔGapp) and a "traffic light" color code to all TMS of OXPHOS membrane proteins, thereby predicting which are more likely to be internalized into mitochondria if allotopically produced. We propose that the design of proteins for allotopic expression must make allowance for μΔGapp maximization of highly hydrophobic TMS in polypeptides whose corresponding genes have not been transferred to the nucleus in some organisms.
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Affiliation(s)
- Felipe Nieto-Panqueva
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Diana Rubalcava-Gracia
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico; Division of Molecular Metabolism, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Patrice P Hamel
- Department of Molecular Genetics and Department of Biological Chemistry and Pharmacology, Ohio State University, Columbus, OH, USA; Vellore Institute of Technology (VIT), School of BioScience and Technology, Vellore, Tamil Nadu, India
| | - Diego González-Halphen
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico.
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Pyrih J, Hammond M, Alves A, Dean S, Sunter JD, Wheeler RJ, Gull K, Lukeš J. Comprehensive sub-mitochondrial protein map of the parasitic protist Trypanosoma brucei defines critical features of organellar biology. Cell Rep 2023; 42:113083. [PMID: 37669165 DOI: 10.1016/j.celrep.2023.113083] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Revised: 06/30/2023] [Accepted: 08/17/2023] [Indexed: 09/07/2023] Open
Abstract
We have generated a high-confidence mitochondrial proteome (MitoTag) of the Trypanosoma brucei procyclic stage containing 1,239 proteins. For 337 of these, a mitochondrial localization had not been described before. We use the TrypTag dataset as a foundation and take advantage of the properties of the fluorescent protein tag that causes aberrant but fortuitous accumulation of tagged matrix and inner membrane proteins near the kinetoplast (mitochondrial DNA). Combined with transmembrane domain predictions, this characteristic allowed categorization of 1,053 proteins into mitochondrial sub-compartments, the detection of unique matrix-localized fucose and methionine synthesis, and the identification of new kinetoplast proteins, which showed kinetoplast-linked pyrimidine synthesis. Moreover, disruption of targeting signals by tagging allowed mapping of the mode of protein targeting to these sub-compartments, identifying a set of C-tail anchored outer mitochondrial membrane proteins and mitochondrial carriers likely employing multiple target peptides. This dataset represents a comprehensive, updated mapping of the mitochondrion.
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Affiliation(s)
- Jan Pyrih
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic; Department of Biochemistry, University of Cambridge, Cambridge, UK; Faculty of Science, University of Ostrava, Ostrava, Czech Republic.
| | - Michael Hammond
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic
| | | | - Samuel Dean
- Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
| | | | - Richard John Wheeler
- Peter Medawar Building for Pathogen Research, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Keith Gull
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Julius Lukeš
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic.
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Darden C, Donkor J, Korolkova O, Khan Barozai MY, Chaudhuri M. Distinct structural motifs are necessary for targeting and import of Tim17 in Trypanosoma brucei mitochondrion. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.07.548172. [PMID: 37461662 PMCID: PMC10350046 DOI: 10.1101/2023.07.07.548172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2024]
Abstract
Nuclear-encoded mitochondrial proteins are correctly translocated to their proper sub-mitochondrial destination using location specific mitochondrial targeting signals (MTSs) and via multi-protein import machineries (translocases) in the outer and inner mitochondrial membranes (TOM and TIMs, respectively). However, MTSs of multi-pass Tims are less defined. Here we report the characterization of the MTSs of Trypanosoma brucei Tim17 (TbTim17), an essential component of the most divergent TIM complex. TbTim17 possesses a characteristic secondary structure including four predicted transmembrane (TM) domains in the center with hydrophilic N- and C-termini. After examining mitochondrial localization of various deletion and site-directed mutants of TbTim17 in T. brucei using subcellular fractionation and confocal microscopy we located at least two internal signals, 1) within TM1 (31-50 AAs) and 2) TM4 + Loop 3 (120-136 AAs). Both signals are required for proper targeting and integration of TbTim17 in the membrane. Furthermore, a positively charged residue (K 122 ) is critical for mitochondrial localization of TbTim17. This is the first report of characterizing the internal mitochondrial targeting signals (ITS) for a multipass inner membrane protein in a divergent eukaryote, like T. brucei . Summary Internal targeting signals within the TM1, TM4 with Loop 3, and residue K122 are required collectively for import and integration of TbTim17 in the T. brucei mitochondrion. This information could be utilized to block parasite growth.
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Wenger C, Harsman A, Niemann M, Oeljeklaus S, von Känel C, Calderaro S, Warscheid B, Schneider A. The Mba1 homologue of Trypanosoma brucei is involved in the biogenesis of oxidative phosphorylation complexes. Mol Microbiol 2023; 119:537-550. [PMID: 36829306 DOI: 10.1111/mmi.15048] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Revised: 02/16/2023] [Accepted: 02/21/2023] [Indexed: 02/26/2023]
Abstract
Consistent with other eukaryotes, the Trypanosoma brucei mitochondrial genome encodes mainly hydrophobic core subunits of the oxidative phosphorylation system. These proteins must be co-translationally inserted into the inner mitochondrial membrane and are synthesized by the highly unique trypanosomal mitoribosomes, which have a much higher protein to RNA ratio than any other ribosome. Here, we show that the trypanosomal orthologue of the mitoribosome receptor Mba1 (TbMba1) is essential for normal growth of procyclic trypanosomes but redundant in the bloodstream form, which lacks an oxidative phosphorylation system. Proteomic analyses of TbMba1-depleted mitochondria from procyclic cells revealed reduced levels of many components of the oxidative phosphorylation system, most of which belong to the cytochrome c oxidase (Cox) complex, three subunits of which are mitochondrially encoded. However, the integrity of the mitoribosome and its interaction with the inner membrane were not affected. Pull-down experiments showed that TbMba1 forms a dynamic interaction network that includes the trypanosomal Mdm38/Letm1 orthologue and a trypanosome-specific factor that stabilizes the CoxI and CoxII mRNAs. In summary, our study suggests that the function of Mba1 in the biogenesis of membrane subunits of OXPHOS complexes is conserved among yeast, mammals and trypanosomes, which belong to two eukaryotic supergroups.
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Affiliation(s)
- Christoph Wenger
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
| | - Anke Harsman
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
| | - Moritz Niemann
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
| | - Silke Oeljeklaus
- Faculty of Chemistry and Pharmacy, Biochemistry II, Theodor Boveri-Institute, University of Würzburg, Würzburg, Germany
| | - Corinne von Känel
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
| | - Salvatore Calderaro
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
| | - Bettina Warscheid
- Faculty of Chemistry and Pharmacy, Biochemistry II, Theodor Boveri-Institute, University of Würzburg, Würzburg, Germany.,CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - André Schneider
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland.,Institute for Advanced Study (Wissenschaftskolleg) Berlin, Berlin, Germany
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Fang YK, Vaitová Z, Hampl V. A mitochondrion-free eukaryote contains proteins capable of import into an exogenous mitochondrion-related organelle. Open Biol 2023; 13:220238. [PMID: 36629021 PMCID: PMC9832562 DOI: 10.1098/rsob.220238] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The endobiotic flagellate Monocercomonoides exilis is the only known eukaryote to have lost mitochondria and all its associated proteins in its evolutionary past. This final stage of the mitochondrial evolutionary pathway may serve as a model to explain events at their very beginning such as the initiation of protein import. We have assessed the capability of proteins from this eukaryote to enter emerging mitochondria using a specifically designed in vitro assay. Hydrogenosomes (reduced mitochondria) of Trichomonas vaginalis were incubated with a soluble protein pool derived from a cytosolic fraction of M. exilis, and proteins entering hydrogenosomes were subsequently detected by mass spectrometry. The assay detected 19 specifically and reproducibly imported proteins, and in 14 cases the import was confirmed by the overexpression of their tagged version in T. vaginalis. In most cases, only a small portion of the signal reached the hydrogenosomes, suggesting specific but inefficient transport. Most of these proteins represent enzymes of carbon metabolism, and none exhibited clear signatures of proteins targeted to hydrogenosomes or mitochondria, which is consistent with their inefficient import. The observed phenomenon may resemble a primaeval type of protein import which might play a role in the establishment of the organelle and shaping of its proteome in the initial stages of endosymbiosis.
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Affiliation(s)
- Yi-Kai Fang
- Charles University, Faculty of Science, Department of Parasitology, BIOCEV, Vestec 252 50, Czech Republic
| | - Zuzana Vaitová
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague 160 00, Czech Republic
| | - Vladimir Hampl
- Charles University, Faculty of Science, Department of Parasitology, BIOCEV, Vestec 252 50, Czech Republic
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