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Mechanisms and regulation of protein synthesis in mitochondria. Nat Rev Mol Cell Biol 2021; 22:307-325. [PMID: 33594280 DOI: 10.1038/s41580-021-00332-2] [Citation(s) in RCA: 154] [Impact Index Per Article: 51.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/13/2021] [Indexed: 02/06/2023]
Abstract
Mitochondria are cellular organelles responsible for generation of chemical energy in the process called oxidative phosphorylation. They originate from a bacterial ancestor and maintain their own genome, which is expressed by designated, mitochondrial transcription and translation machineries that differ from those operating for nuclear gene expression. In particular, the mitochondrial protein synthesis machinery is structurally and functionally very different from that governing eukaryotic, cytosolic translation. Despite harbouring their own genetic information, mitochondria are far from being independent of the rest of the cell and, conversely, cellular fitness is closely linked to mitochondrial function. Mitochondria depend heavily on the import of nuclear-encoded proteins for gene expression and function, and hence engage in extensive inter-compartmental crosstalk to regulate their proteome. This connectivity allows mitochondria to adapt to changes in cellular conditions and also mediates responses to stress and mitochondrial dysfunction. With a focus on mammals and yeast, we review fundamental insights that have been made into the biogenesis, architecture and mechanisms of the mitochondrial translation apparatus in the past years owing to the emergence of numerous near-atomic structures and a considerable amount of biochemical work. Moreover, we discuss how cellular mitochondrial protein expression is regulated, including aspects of mRNA and tRNA maturation and stability, roles of auxiliary factors, such as translation regulators, that adapt mitochondrial translation rates, and the importance of inter-compartmental crosstalk with nuclear gene expression and cytosolic translation and how it enables integration of mitochondrial translation into the cellular context.
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Rudler DL, Hughes LA, Viola HM, Hool LC, Rackham O, Filipovska A. Fidelity and coordination of mitochondrial protein synthesis in health and disease. J Physiol 2020; 599:3449-3462. [PMID: 32710561 DOI: 10.1113/jp280359] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 07/07/2020] [Indexed: 12/12/2022] Open
Abstract
The evolutionary acquisition of mitochondria has given rise to the diversity of eukaryotic life. Mitochondria have retained their ancestral α-proteobacterial traits through the maintenance of double membranes and their own circular genome. Their genome varies in size from very large in plants to the smallest in animals and their parasites. The mitochondrial genome encodes essential genes for protein synthesis and has to coordinate its expression with the nuclear genome from which it sources most of the proteins required for mitochondrial biogenesis and function. The mitochondrial protein synthesis machinery is unique because it is encoded by both the nuclear and mitochondrial genomes thereby requiring tight regulation to produce the respiratory complexes that drive oxidative phosphorylation for energy production. The fidelity and coordination of mitochondrial protein synthesis are essential for ATP production. Here we compare and contrast the mitochondrial translation mechanisms in mammals and fungi to bacteria and reveal that their diverse regulation can have unusual impacts on the health and disease of these organisms. We highlight that in mammals the rate of protein synthesis is more important than the fidelity of translation, enabling coordinated biogenesis of the mitochondrial respiratory chain with respiratory chain proteins synthesised by cytoplasmic ribosomes. Changes in mitochondrial protein fidelity can trigger the activation of the diverse cellular signalling networks in fungi and mammals to combat dysfunction in energy conservation. The physiological consequences of altered fidelity of protein synthesis can range from liver regeneration to the onset and development of cardiomyopathy.
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Affiliation(s)
- Danielle L Rudler
- Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia, 6009, Australia.,ARC Centre of Excellence in Synthetic Biology, QEII Medical Centre, Nedlands, Western Australia, 6009, Australia.,Centre for Medical Research, The University of Western Australia, QEII Medical Centre, Nedlands, Western Australia, 6009, Australia
| | - Laetitia A Hughes
- Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia, 6009, Australia.,ARC Centre of Excellence in Synthetic Biology, QEII Medical Centre, Nedlands, Western Australia, 6009, Australia.,Centre for Medical Research, The University of Western Australia, QEII Medical Centre, Nedlands, Western Australia, 6009, Australia
| | - Helena M Viola
- School of Human Sciences, University of Western Australia, 35 Stirling Highway, Nedlands, Western Australia, 6009, Australia
| | - Livia C Hool
- School of Human Sciences, University of Western Australia, 35 Stirling Highway, Nedlands, Western Australia, 6009, Australia.,Victor Chang Cardiac Research Institute, Sydney, NSW, Australia
| | - Oliver Rackham
- Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia, 6009, Australia.,ARC Centre of Excellence in Synthetic Biology, QEII Medical Centre, Nedlands, Western Australia, 6009, Australia.,School of Pharmacy and Biomedical Sciences, Curtin University, Bentley, Western Australia, 6102, Australia.,Curtin Health Innovation Research Institute, Curtin University, Bentley, Western Australia, 6102, Australia.,Telethon Kids Institute, Northern Entrance, Perth Children's Hospital, 15 Hospital Avenue, Nedlands, Western Australia, Australia
| | - Aleksandra Filipovska
- Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia, 6009, Australia.,ARC Centre of Excellence in Synthetic Biology, QEII Medical Centre, Nedlands, Western Australia, 6009, Australia.,Centre for Medical Research, The University of Western Australia, QEII Medical Centre, Nedlands, Western Australia, 6009, Australia.,Telethon Kids Institute, Northern Entrance, Perth Children's Hospital, 15 Hospital Avenue, Nedlands, Western Australia, Australia.,School of Molecular Sciences, University of Western Australia, Crawley, Western Australia, 6009, Australia
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Yeast Mitochondrial Translation Initiation Factor 3 Interacts with Pet111p to Promote COX2 mRNA Translation. Int J Mol Sci 2020; 21:ijms21103414. [PMID: 32408541 PMCID: PMC7279496 DOI: 10.3390/ijms21103414] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Revised: 05/08/2020] [Accepted: 05/11/2020] [Indexed: 11/17/2022] Open
Abstract
Mitochondrial genomes code for several core components of respiratory chain complexes. Thus, mitochondrial translation is of great importance for the organelle as well as for the whole cell. In yeast, mitochondrial translation initiation factor 3, Aim23p, is not essential for the organellar protein synthesis; however, its absence leads to a significant quantitative imbalance of the mitochondrial translation products. This fact points to a possible specific action of Aim23p on the biosynthesis of some mitochondrial protein species. In this work, we examined such peculiar effects of Aim23p in relation to yeast mitochondrial COX2 mRNA translation. We show that Aim23p is indispensable to this process. According to our data, this is mediated by Aimp23p interaction with the known specific factor of the COX2 mRNA translation, Pet111p. If there is no Aim23p in the yeast cells, an increased amount of Pet111p ensures proper COX2 mRNA translation. Our results demonstrate the additional non-canonical function of initiation factor 3 in yeast mitochondrial translation.
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Rudler DL, Hughes LA, Perks KL, Richman TR, Kuznetsova I, Ermer JA, Abudulai LN, Shearwood AMJ, Viola HM, Hool LC, Siira SJ, Rackham O, Filipovska A. Fidelity of translation initiation is required for coordinated respiratory complex assembly. SCIENCE ADVANCES 2019; 5:eaay2118. [PMID: 31903419 PMCID: PMC6924987 DOI: 10.1126/sciadv.aay2118] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 10/30/2019] [Indexed: 05/22/2023]
Abstract
Mammalian mitochondrial ribosomes are unique molecular machines that translate 11 leaderless mRNAs; however, it is not clear how mitoribosomes initiate translation, since mitochondrial mRNAs lack untranslated regions. Mitochondrial translation initiation shares similarities with prokaryotes, such as the formation of a ternary complex of fMet-tRNAMet, mRNA and the 28S subunit, but differs in the requirements for initiation factors. Mitochondria have two initiation factors: MTIF2, which closes the decoding center and stabilizes the binding of the fMet-tRNAMet to the leaderless mRNAs, and MTIF3, whose role is not clear. We show that MTIF3 is essential for survival and that heart- and skeletal muscle-specific loss of MTIF3 causes cardiomyopathy. We identify increased but uncoordinated mitochondrial protein synthesis in mice lacking MTIF3, resulting in loss of specific respiratory complexes. Ribosome profiling shows that MTIF3 is required for recognition and regulation of translation initiation of mitochondrial mRNAs and for coordinated assembly of OXPHOS complexes in vivo.
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Affiliation(s)
- Danielle L. Rudler
- Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
- Centre for Medical Research, The University of Western Australia, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
| | - Laetitia A. Hughes
- Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
- Centre for Medical Research, The University of Western Australia, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
| | - Kara L. Perks
- Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
- Centre for Medical Research, The University of Western Australia, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
| | - Tara R. Richman
- Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
- Centre for Medical Research, The University of Western Australia, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
| | - Irina Kuznetsova
- Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
- Centre for Medical Research, The University of Western Australia, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
| | - Judith A. Ermer
- Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
- Centre for Medical Research, The University of Western Australia, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
| | - Laila N. Abudulai
- Centre for Microscopy, Characterisation and Analysis and School of Biomedical Sciences, The University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Anne-Marie J. Shearwood
- Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
- Centre for Medical Research, The University of Western Australia, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
| | - Helena M. Viola
- School of Human Sciences (Physiology), The University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Livia C. Hool
- School of Human Sciences (Physiology), The University of Western Australia, Crawley, Western Australia 6009, Australia
- Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales 2010, Australia
| | - Stefan J. Siira
- Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
- Centre for Medical Research, The University of Western Australia, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
| | - Oliver Rackham
- Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
- School of Pharmacy and Biomedical Sciences, Curtin University, Bentley, Western Australia 6102, Australia
- Curtin Health Innovation Research Institute, Curtin University, Bentley, Western Australia 6102, Australia
| | - Aleksandra Filipovska
- Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
- Centre for Medical Research, The University of Western Australia, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
- School of Molecular Sciences, The University of Western Australia, Crawley, Western Australia 6009, Australia
- Corresponding author.
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Ayyub SA, Varshney U. Translation initiation in mammalian mitochondria- a prokaryotic perspective. RNA Biol 2019; 17:165-175. [PMID: 31696767 DOI: 10.1080/15476286.2019.1690099] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
ATP is generated in mitochondria of eukaryotic cells by oxidative phosphorylation (OXPHOS). The OXPHOS complex, which is crucial for cellular metabolism, comprises of both nuclear and mitochondrially encoded subunits. Also, the occurrence of several pathologies because of mutations in the mitochondrial translation apparatus indicates the importance of mitochondrial translation and its regulation. The mitochondrial translation apparatus is similar to its prokaryotic counterpart due to a common origin of evolution. However, mitochondrial translation has diverged from prokaryotic translation in many ways by reductive evolution. In this review, we focus on mammalian mitochondrial translation initiation, a highly regulated step of translation, and present a comparison with prokaryotic translation.
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Affiliation(s)
- Shreya Ahana Ayyub
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Umesh Varshney
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India.,Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
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Govindan A, Ayyub SA, Varshney U. Sustenance of Escherichia coli on a single tRNAMet. Nucleic Acids Res 2019; 46:11566-11574. [PMID: 30256973 PMCID: PMC6265465 DOI: 10.1093/nar/gky859] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Accepted: 09/12/2018] [Indexed: 11/16/2022] Open
Abstract
Living organisms possess two types of tRNAs for methionine. Initiator tRNAs bind directly into the ribosomal P-site to initiate protein synthesis, and the elongators bind to the A-site during the elongation step. Eubacterial initiators (tRNAfMet) are unique in that the methionine attached to them is formylated to facilitate their binding to initiation factor 2 (IF2), and to preclude them from binding to elongation factor Tu (EFTu). However, in mammalian mitochondria, protein synthesis proceeds with a single dual function tRNAMet. Escherichia coli possesses four tRNAfMet (initiator) and two tRNAMet (elongator) genes. Free-living organisms possessing the mitochondrion like system of single tRNAMet are unknown. We characterized mutants of E. coli tRNAfMet that function both as initiators and elongators. We show that some of the tRNAfMet mutants sustain E. coli lacking all four tRNAfMet and both tRNAMet genes, providing a basis for natural occurrence of mitochondria like situation in free living organisms. The tRNA mutants show in vivo binding to both IF2 and EFTu, indicating how they carry out these otherwise mutually exclusive functions by precise regulation of their in vivo formylation. Our results provide insights into how distinct initiator and elongator methionine tRNAs might have evolved from a single ‘dual function’ tRNA.
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Affiliation(s)
- Ashwin Govindan
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India
| | - Shreya Ahana Ayyub
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India
| | - Umesh Varshney
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India.,Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India
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Koripella RK, Sharma MR, Haque ME, Risteff P, Spremulli LL, Agrawal RK. Structure of Human Mitochondrial Translation Initiation Factor 3 Bound to the Small Ribosomal Subunit. iScience 2019; 12:76-86. [PMID: 30677741 PMCID: PMC6352543 DOI: 10.1016/j.isci.2018.12.030] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 12/11/2018] [Accepted: 12/27/2018] [Indexed: 11/20/2022] Open
Abstract
The human mitochondrial translational initiation factor 3 (IF3mt) carries mitochondrial-specific amino acid extensions at both its N and C termini (N- and C-terminal extensions [NTE and CTE, respectively]), when compared with its eubacterial counterpart. Here we present 3.3- to 3.5-Å-resolution cryoelectron microscopic structures of the mammalian 28S mitoribosomal subunit in complex with human IF3mt. Unique contacts observed between the 28S subunit and N-terminal domain of IF3mt explain its unusually high affinity for the 28S subunit, whereas the position of the mito-specific NTE suggests NTE's role in binding of initiator tRNA to the 28S subunit. The location of the C-terminal domain (CTD) clarifies its anti-association activity, whereas the orientation of the mito-specific CTE provides a mechanistic explanation for its role in destabilizing initiator tRNA in the absence of mRNA. Furthermore, our structure hints at a possible role of the CTD in recruiting leaderless mRNAs for translation initiation. Our findings highlight unique features of IF3mt in mitochondrial translation initiation. High-resolution cryo-EM study of the mammalian 28S mitoribosome-IF3mt complex Interaction between the 28S and IF3mt's NTD explains NTD's unusual high affinity Provides insights into role of IF3mt's N-terminal extension in initiator tRNA binding Provides insights into roles of IF3mt's CTD and C-terminal extension in mRNA sensing
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Affiliation(s)
- Ravi K Koripella
- Division of Translational Medicine, Wadsworth Center, New York State Department of Health, Albany, NY 12201-0509, USA
| | - Manjuli R Sharma
- Division of Translational Medicine, Wadsworth Center, New York State Department of Health, Albany, NY 12201-0509, USA
| | - Md Emdadul Haque
- Department of Chemistry, Campus Box 3290, University of North Carolina, Chapel Hill, NC, USA
| | - Paul Risteff
- Division of Translational Medicine, Wadsworth Center, New York State Department of Health, Albany, NY 12201-0509, USA
| | - Linda L Spremulli
- Department of Chemistry, Campus Box 3290, University of North Carolina, Chapel Hill, NC, USA
| | - Rajendra K Agrawal
- Division of Translational Medicine, Wadsworth Center, New York State Department of Health, Albany, NY 12201-0509, USA; Department of Biomedical Sciences, School of Public Health, University at Albany, SUNY, Albany, NY, USA.
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Levitskii S, Derbikova K, Baleva MV, Kuzmenko A, Golovin AV, Chicherin I, Krasheninnikov IA, Kamenski P. 60S dynamic state of bacterial ribosome is fixed by yeast mitochondrial initiation factor 3. PeerJ 2018; 6:e5620. [PMID: 30245939 PMCID: PMC6147165 DOI: 10.7717/peerj.5620] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 08/21/2018] [Indexed: 11/24/2022] Open
Abstract
The processes of association and dissociation of ribosomal subunits are of great importance for the protein biosynthesis. The mechanistic details of these processes, however, are not well known. In bacteria, upon translation termination, the ribosome dissociates into subunits which is necessary for its further involvement into new initiation step. The dissociated state of the ribosome is maintained by initiation factor 3 (IF3) which binds to free small subunits and prevents their premature association with large subunits. In this work, we have exchanged IF3 in Escherichia coli cells by its ortholog from Saccharomyces cerevisiae mitochondria (Aim23p) and showed that yeast protein cannot functionally substitute the bacterial one and is even slightly toxic for bacterial cells. Our in vitro experiments have demonstrated that Aim23p does not split E. coli ribosomes into subunits. Instead, it fixes a state of ribosomes characterized by sedimentation coefficient about 60S which is not a stable structure but rather reflects a shift of dynamic equilibrium between associated and dissociated states of the ribosome. Mitochondria-specific terminal extensions of Aim23p are necessary for “60S state” formation, and molecular modeling results point out that these extensions might stabilize the position of the protein on the bacterial ribosome.
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Affiliation(s)
| | | | - Maria V Baleva
- Faculty of Biology, Moscow State University, Moscow, Russia
| | - Anton Kuzmenko
- Faculty of Biology, Moscow State University, Moscow, Russia
| | - Andrey V Golovin
- Faculty of Bioengineering and Bioinformatics, Moscow State University, Moscow, Russia.,Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow, Russia.,Faculty of Computer Science, Higher School of Economics, Moscow, Russia
| | - Ivan Chicherin
- Faculty of Biology, Moscow State University, Moscow, Russia
| | | | - Piotr Kamenski
- Faculty of Biology, Moscow State University, Moscow, Russia
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