Evidence that the fragmented ribosomal RNAs of <i>Chlamydomonas</i> mitochondria are associated with ribosomes

Denovan‐Wright, Eileen M.; Lee, William R.

doi:10.1016/0014-5793(95)00837-y

Cited by 13 publications

(6 citation statements)

References 15 publications

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“…When initially characterized 30 years ago 17 , Chlamydomonas mitoribosome rRNA fragmentation represented the earliest example that an rRNA does not need to be continuous in order to be functional 20 . Although it was predicted that the rRNA fragments would somehow be integrated into a functional ribosome 18 , it is enigmatic how these fragments are recruited, interact with each other, and are stabilized to form the 3D mitoribosome structure.…”

Section: Introductionmentioning

confidence: 99%

How to build a ribosome from RNA fragments in Chlamydomonas mitochondria

et al. 2021

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Mitochondria are the powerhouse of eukaryotic cells. They possess their own gene expression machineries where highly divergent and specialized ribosomes, named hereafter mitoribosomes, translate the few essential messenger RNAs still encoded by mitochondrial genomes. Here, we present a biochemical and structural characterization of the mitoribosome in the model green alga Chlamydomonas reinhardtii, as well as a functional study of some of its specific components. Single particle cryo-electron microscopy resolves how the Chlamydomonas mitoribosome is assembled from 13 rRNA fragments encoded by separate non-contiguous gene pieces. Additional proteins, mainly OPR, PPR and mTERF helical repeat proteins, are found in Chlamydomonas mitoribosome, revealing the structure of an OPR protein in complex with its RNA binding partner. Targeted amiRNA silencing indicates that these ribosomal proteins are required for mitoribosome integrity. Finally, we use cryo-electron tomography to show that Chlamydomonas mitoribosomes are attached to the inner mitochondrial membrane via two contact points mediated by Chlamydomonas-specific proteins. Our study expands our understanding of mitoribosome diversity and the various strategies these specialized molecular machines adopt for membrane tethering.

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Section: Introductionmentioning

confidence: 99%

How to build a ribosome from RNA fragments in Chlamydomonas mitochondria

et al. 2021

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“…Boer and Gray (1988) have proposed that the rRNA segments probably assemble and associate noncovalently to produce the RNAs of the small and the large ribosomal subunits. The results obtained by Denovan-Wright and Lee (1995) in C. eugametos (a species in which the mitochondrial rRNA genes are also discontinuous) point in that direction. The present data demonstrate that the rRNA gene pieces in C. reinhardtii mitochondrial DNA are functional since the m mutation in the L5 module acts as a suppressor of the dum19 mutation.…”

Section: Discussionmentioning

confidence: 85%

A mutation in the GTPase domain of the large subunit rRNA is involved in the suppression of a –1T frameshift mutation affecting a mitochondrial gene in Chlamydomonas reinhardtii

Matagne

Baurain

2001

Mol Gen Genomics

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The dum19 mutation isolated in Chlamydomonas reinhardtii is due to the deletion of one T at codon 152 of the mitochondrial cox1 gene sequence. Phenotypically, the dum19 mutant is characterized by a lack of cytochrome c oxidase activity and is unable to grow under heterotrophic conditions. A spontaneous pseudo-revertant that grows slowly in the dark was isolated from the dum19 mutant strain. A genetic and molecular analysis allowed us to demonstrate that the revertant phenotype is the consequence of two additional mutations that together act as a frameshift suppressor: an m mutation affecting a mitochondrial gene other than cox1 and an n mutation affecting a nuclear gene. On its own the n mutation does not act as a suppressor, whereas the m mutation very slightly compensates for the effect of the -1T mutation. Sequencing analysis showed that the m mutation affects the GTPase-associated domain of the large subunit (LSU) of mitochondrial rRNA. Surprisingly, two substitutions, A 1090 to G and A 1098 to C, were found in the LSU rRNA of the revertant, the latter one being already present in the dum19 mutant strain itself. The A 1090 to G substitution is thus involved in the suppression of the frameshift mutation, but it is not clear whether the change at position 1098 is also required for the expression of the suppressed phenotype. To our knowledge, this is the first example of a mutation in the GTPase-associated domain acting as a suppressor of a frameshift mutation.

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“…3B). Previous studies of the C. reinhardtii mitochondrial genome and rRNAs always failed to identify this rRNA as a putative 5S (Boer and Gray, 1988;Denovan-Wright and Lee, 1995;Nedelcu, 1997;Salinas-Giegé et al, 2017). While L3a likely derives from an ancestral bacterial 5S rRNA, it is highly degenerated; very little of the primary sequence is conserved with other 5S rRNAs (Fig.…”

Section: Fragmented Ribosomal Rnas Are Assembled To Reconstitute the Core Of Chlamydomonas Mitoribosomementioning

confidence: 97%

“…In contrast to vascular plants, or Viridiplantae in general, which are characterized by gene-rich and largely expanded mitochondrial (mt)-genomes, C. reinhardtii possess a small linear mt-genome of 16kb. It only encodes eight proteins (all membraneembedded components of the respiratory chain), three transfer RNAs (tRNAs) and, most intriguingly, non-contiguous pieces of the large subunit (LSU) and small subunit (SSU) ribosomal RNAs (rRNAs), scrambled across the genome (Boer and Gray, 1988;Denovan-Wright and Lee, 1995;Salinas-Giegé et al, 2017). The mt-genome is transcribed as two polycistronic primary transcripts synthesized from opposite strands (Boer and Gray, 1988;Salinas-Giegé et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

“…Individual transcripts are then generated from the primary transcripts to produce mature, functional RNAs. Although it was predicted that the rRNA fragments would somehow be integrated into a functional ribosome (Denovan-Wright and Lee, 1995), it is enigmatic how these fragments are recruited, interact with each other, and are stabilized to form the 3D mitoribosome structure.…”

Section: Introductionmentioning

confidence: 99%

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The Chlamydomonas mitochondrial ribosome: how to build a ribosome from RNA fragments

Waltz

Salinas‐Giegé

Englmeier

et al. 2021

Preprint

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Mitochondria are the powerhouse of eukaryotic cells. They possess their own gene expression machineries where highly divergent and specialized ribosomes, named hereafter mitoribosomes, translate the few essential messenger RNAs still encoded by mitochondrial genomes. Here, we present a biochemical and structural characterization of the mitoribosome in the model green alga Chlamydomonas reinhardtii, as well as a functional study of some of its specific components. Single particle cryo-electron microscopy resolves how the Chlamydomonas mitoribosome is assembled from 13 rRNA fragments encoded by separate non-contiguous gene pieces. Novel proteins, mainly helical repeat proteins, including OPR, PPR and mTERF proteins are found in Chlamydomonas mitoribosome, revealing the first structure of an OPR protein in complex with its RNA target. Targeted amiRNA silencing indicated that the novel ribosomal proteins are required for mitoribosome integrity. Finally, we use cryo-electron tomography to show that Chlamydomonas mitoribosomes are attached to the mitochondrial inner membrane via two contact points mediated by Chlamydomonas-specific proteins. Our study expands our understanding of the mitoribosome diversity and the various strategies they adopt for membrane tethering.

show abstract

Evidence that the fragmented ribosomal RNAs of Chlamydomonas mitochondria are associated with ribosomes

Cited by 13 publications

References 15 publications

How to build a ribosome from RNA fragments in Chlamydomonas mitochondria

How to build a ribosome from RNA fragments in Chlamydomonas mitochondria

A mutation in the GTPase domain of the large subunit rRNA is involved in the suppression of a –1T frameshift mutation affecting a mitochondrial gene in Chlamydomonas reinhardtii

The Chlamydomonas mitochondrial ribosome: how to build a ribosome from RNA fragments

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