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High-resolution imaging reveals compartmentalisation of mitochondrial protein synthesis in cultured human cells

Lookup NU author(s): Matt Zorkau, Dr Christin Albus, Dr Rolando Berlinguer Palmini, Professor Zofia Chrzanowska-Lightowlers, Professor Robert Lightowlers

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

Human mitochondria contain their own genome, mitochondrial DNA, that is expressed in the mitochondrial matrix. This genome encodes 13 vital polypeptides that are components of the multisubunit complexes that couple oxidative phosphorylation (OXPHOS). The inner mitochondrial membrane that houses these complexes comprises the inner boundary membrane that runs parallel to the outer membrane, infoldings that form the cristae membranes, and the cristae junctions that separate the two. It is in these cristae membranes that the OXPHOS complexes have been shown to reside in various species. The majority of the OXPHOS subunits are nuclear-encoded and must therefore be imported from the cytosol through the outer membrane at contact sites with the inner boundary membrane. As the mitochondrially encoded components are also integral members of these complexes, where does protein synthesis occur? As transcription, mRNA processing, maturation, and at least part of the mitoribosome assembly process occur at the nucleoid and the spatially juxtaposed mitochondrial RNA granules, is protein synthesis also performed at the RNA granules close to these entities, or does it occur distal to these sites? We have adapted a click chemistry-based method coupled with stimulated emission depletion nanoscopy to address these questions. We report that, in human cells in culture, within the limits of our methodology, the majority of mitochondrial protein synthesis is detected at the cristae membranes and is spatially separated from the sites of RNA processing and maturation.


Publication metadata

Author(s): Zorkau M, Albus CA, Berlinguer-Palmini R, Chrzanowska-Lightowlers ZMA, RN Lightowlers

Publication type: Article

Publication status: Published

Journal: PNAS

Year: 2021

Volume: 118

Issue: 6

Online publication date: 01/02/2021

Acceptance date: 18/12/2020

Date deposited: 04/03/2021

ISSN (electronic): 0027-8424

Publisher: National Academy of Sciences

URL: https://doi.org/10.1073/pnas.2008778118

DOI: 10.1073/pnas.2008778118


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