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dc.contributor.author
Bieri, Philipp
dc.contributor.supervisor
Ban, Nenad
dc.contributor.supervisor
Ishikawa, Takashi
dc.contributor.supervisor
Pilhofer, Martin
dc.contributor.supervisor
Boehringer, Daniel
dc.date.accessioned
2018-10-31T10:28:05Z
dc.date.available
2017-10-31T08:41:14Z
dc.date.available
2017-10-31T10:04:50Z
dc.date.available
2018-10-30T14:33:31Z
dc.date.available
2018-10-31T10:28:05Z
dc.date.issued
2017
dc.identifier.uri
http://hdl.handle.net/20.500.11850/202600
dc.identifier.doi
10.3929/ethz-b-000202600
dc.description.abstract
Mitochondria and chloroplasts are cellular organelles with important functions in the energy metabolism of eukaryotic cells by hosting the protein complexes catalysing the oxidative phosphorylation and the photosynthetic reaction, respectively. They have independently evolved by the endosymbiosis of ancestral bacteria with eukaryotic progenitor cells. Essential membrane proteins of the oxidative phosphorylation and the photosynthesis machinery are still encoded on the residual organellar genomes and synthesized by the in-house translation apparatus, the mitochondrial and the chloroplast ribosome, respectively. Although sharing a common ancestor, mitoribosomes have a dramatically diverged composition and architecture in comparison to contemporary bacterial ribosomes. The high-resolution cryo-EM structures of the complete mammalian 55S mitoribosome and its 39S large and 28S small subunits presented in the first and second chapter of this thesis reveal their unique structural features and provide many important insights into the mechanism of mitochondrial protein biosynthesis. The mammalian 55S mitoribosome has a highly reduced rRNA, and the bacterial 5S rRNA is replaced by a tRNA molecule (CP tRNA) that was incorporated as a permanent part of the central protuberance. In addition, new ribosomal proteins, 28 in total, were acquired to the 55S mitoribosome providing structural stability of the reduced rRNA core and additional functionality, for example, in mRNA recruitment, intersubunit contacts, and membrane attachment. Mutations in mitoribosomal components can lead to severe human diseases that can now be understood on molecular level by inspecting the high-resolution structure of the mammalian 55S mitoribosome. In chloroplasts of plants and algae, the protein biosynthesis is coordinated with the photosynthetic activity defined by the day-night cycle and is mainly regulated at the level of translation. The high-resolution cryo-EM structure of the spinach chloroplast 70S ribosome presented in the third chapter of this thesis shows the plastid translation factor pY bound to the mRNA channel of the small subunit, where it blocks the translation initiation and stabilizes the ribosome in a non-rotated conformation during the dark phase of the day. Further, the structure reveals the plastid-specific ribosomal elements including five additional ribosomal proteins and extensions of ribosomal proteins with bacterial homologs that either play an important role in translation regulation or in structural stability. The rRNA molecules of the large subunit are fragmented to include an additional 4.5S rRNA and two strand breaks in the 23S rRNA, called hidden breaks. Taken together, the work in this thesis reveals the unique architecture of the mammalian 55S mitoribosome and the plant chloroplast 70S ribosome and provides novel insights into the mechanism of organellar protein biosynthesis and the evolution of organellar ribosomes.
en_US
dc.format
application/pdf
en_US
dc.language.iso
en
en_US
dc.publisher
ETH Zurich
en_US
dc.rights.uri
http://rightsstatements.org/page/InC-NC/1.0/
dc.subject
ribosome
en_US
dc.subject
translation
en_US
dc.subject
chloroplast
en_US
dc.subject
mitochondria
en_US
dc.subject
cryo-EM
en_US
dc.subject
single particle analysis
en_US
dc.subject
mitoribosome
en_US
dc.subject
chloroplast ribosome
en_US
dc.subject
organellar protein biosynthesis
en_US
dc.subject
evolution of organellar ribosomes
en_US
dc.subject
endosymbiosis
en_US
dc.title
Unique Architectural and Evolutionary Features of the Mammalian Mitochondrial and the Plant Chloroplast Ribosome Revealed by Cryo-Electron Microscopy
en_US
dc.type
Doctoral Thesis
dc.rights.license
In Copyright - Non-Commercial Use Permitted
dc.date.published
2017-10-31
ethz.size
214 p.
en_US
ethz.code.ddc
DDC - DDC::5 - Science::570 - Life sciences
en_US
ethz.identifier.diss
24671
en_US
ethz.publication.place
Zurich
en_US
ethz.publication.status
published
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02030 - Dep. Biologie / Dep. of Biology::02521 - Inst. f. Molekularbiologie u. Biophysik / Inst. Molecular Biology and Biophysics::03556 - Ban, Nenad / Ban, Nenad
en_US
ethz.leitzahl.certified
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02030 - Dep. Biologie / Dep. of Biology::02521 - Inst. f. Molekularbiologie u. Biophysik / Inst. Molecular Biology and Biophysics::03556 - Ban, Nenad / Ban, Nenad
en_US
ethz.relation.isCitedBy
10.1126/science.aaa3872
ethz.relation.isCitedBy
10.1038/nature13895
ethz.relation.isCitedBy
10.15252/embj.201695959
ethz.date.deposited
2017-10-31T08:41:15Z
ethz.source
FORM
ethz.eth
yes
en_US
ethz.availability
Open access
en_US
ethz.date.embargoend
2018-10-31
ethz.rosetta.installDate
2017-10-31T10:05:25Z
ethz.rosetta.lastUpdated
2018-10-31T10:29:06Z
ethz.rosetta.versionExported
true
ethz.COinS
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