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Dalla Rosa I, Durigon R, Pearce SF, Rorbach J, Hirst EMA, Vidoni S, Reyes A, Brea-Calvo G, Minczuk M, Woellhaf MW, Herrmann JM, Huynen MA, Holt IJ, Spinazzola A. MPV17L2 is required for ribosome assembly in mitochondria. Nucleic Acids Res 2014; 42:8500-15. [PMID: 24948607 PMCID: PMC4117752 DOI: 10.1093/nar/gku513] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
MPV17 is a mitochondrial protein of unknown function, and mutations in MPV17 are associated with mitochondrial deoxyribonucleic acid (DNA) maintenance disorders. Here we investigated its most similar relative, MPV17L2, which is also annotated as a mitochondrial protein. Mitochondrial fractionation analyses demonstrate MPV17L2 is an integral inner membrane protein, like MPV17. However, unlike MPV17, MPV17L2 is dependent on mitochondrial DNA, as it is absent from ρ(0) cells, and co-sediments on sucrose gradients with the large subunit of the mitochondrial ribosome and the monosome. Gene silencing of MPV17L2 results in marked decreases in the monosome and both subunits of the mitochondrial ribosome, leading to impaired protein synthesis in the mitochondria. Depletion of MPV17L2 also induces mitochondrial DNA aggregation. The DNA and ribosome phenotypes are linked, as in the absence of MPV17L2 proteins of the small subunit of the mitochondrial ribosome are trapped in the enlarged nucleoids, in contrast to a component of the large subunit. These findings suggest MPV17L2 contributes to the biogenesis of the mitochondrial ribosome, uniting the two subunits to create the translationally competent monosome, and provide evidence that assembly of the small subunit of the mitochondrial ribosome occurs at the nucleoid.
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Affiliation(s)
- Ilaria Dalla Rosa
- MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Romina Durigon
- MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Sarah F Pearce
- MRC Mitochondrial Biology Unit, Wellcome Trust-MRC Building, Hills Road, Cambridge CB2 0XY, UK
| | - Joanna Rorbach
- MRC Mitochondrial Biology Unit, Wellcome Trust-MRC Building, Hills Road, Cambridge CB2 0XY, UK
| | | | - Sara Vidoni
- MRC Mitochondrial Biology Unit, Wellcome Trust-MRC Building, Hills Road, Cambridge CB2 0XY, UK
| | - Aurelio Reyes
- MRC Mitochondrial Biology Unit, Wellcome Trust-MRC Building, Hills Road, Cambridge CB2 0XY, UK
| | - Gloria Brea-Calvo
- MRC Mitochondrial Biology Unit, Wellcome Trust-MRC Building, Hills Road, Cambridge CB2 0XY, UK
| | - Michal Minczuk
- MRC Mitochondrial Biology Unit, Wellcome Trust-MRC Building, Hills Road, Cambridge CB2 0XY, UK
| | - Michael W Woellhaf
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | | | - Martijn A Huynen
- Centre for Molecular and Biomolecular Informatics, Radboud University Medical Centre, Geert Grooteplein Zuid 26-28, 6525 GA Nijmegen, Netherlands
| | - Ian J Holt
- MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
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Chapter 2 Reversed-phase and hydrophobic interaction chromatography of carbohydrates and glycoconjugates. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s0301-4770(02)80027-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Chapter 2 Reversed-Phase and Hydrophobic Interaction Chromatography of Carbohydrates and Glycoconjugates. ACTA ACUST UNITED AC 1995. [DOI: 10.1016/s0301-4770(08)60507-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Collier E, Carpentier JL, Beitz L, Carol H, Taylor SI, Gorden P. Specific glycosylation site mutations of the insulin receptor alpha subunit impair intracellular transport. Biochemistry 1993; 32:7818-23. [PMID: 8347587 DOI: 10.1021/bi00081a029] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The insulin receptor is a transmembrane protein found on multiple cell types. This receptor is synthesized as a 190-kDa proreceptor which is cleaved to produce mature alpha and beta subunits. The proreceptor contains 18 potential sites for N-linked glycosylation: 14 on the alpha subunit and 4 on the beta subunit. The codons for asparagine in the first four sites at the amino terminus of the alpha subunit were mutated to code for glutamine. This mutant receptor cDNA was stably transfected into NIH 3T3 cells. The insulin receptor produced in these cells remained in the proreceptor form; no mature alpha and beta subunits were produced. The proreceptor was slightly smaller on SDS-PAGE gels than the wild-type proreceptor and contained four less oligosaccharide chains by tryptic peptide mapping. The carbohydrate chains on the mutant proreceptor remained endoglycosidase H sensitive. However, in the presence of brefeldin A, these oligosaccharide chains could be processed to endoglycosidase H resistant chains. By immunofluorescence, the mutant proreceptor was shown to be localized to the endoplasmic reticulum. No insulin receptors could be found on the cell-surface either with cell surface labeling with biotin or with 125I-insulin binding. Thus, glycosylation of the first four N-linked glycosylation sites of the insulin receptor is necessary for the proper processing and intracellular transport of the receptor. This is in contrast to glycosylation at the four sites on the beta subunit which appear not to be important for processing but necessary for signal transduction. Therefore, N-linked glycosylation of the insulin receptor at specific sites has multiple distinctive roles.
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Affiliation(s)
- E Collier
- Diabetes Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
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