Analysis of translating mitoribosome reveals functional characteristics of translation in mitochondria of fungi

Itoh, Yuzuru; Naschberger, Andreas; Mortezaei, Narges; Herrmann, Johannes M.; Amunts, Alexey

doi:10.1101/2020.01.31.929331

Cited by 10 publications

(13 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…From the density we identified three additional proteins below the L7/L12 stalk: a homolog of the human mitoribosome assembly factor MALSU1, a LYR (leucine-tyrosine-arginine) motif containing protein L0R8F8, as well as an associated mt-ACP (mt-ACP1) (Figs 1, 2 and 4). In human and fungi, protein trans-acting factors in this region were shown to be involved in the last assembly stage of the mitoribosome, preventing association of the mtSSU (Brown et al 2017;Itoh et al 2020). In our structure, the module is further stabilized by mL85 to provide a steric hindrance, consistent with the previously suggested mechanism.…”

Section: Maturation Of the L7/l12 Stalksupporting

confidence: 88%

“…A functional mtLSU requires a folded rRNA core, a flexible L1 stalk that is involved in tRNA movement, an extended L7/L12 protrusion for binding of translational factors, and a proteinaceous CP formed by mitochondria-specific elements involved in tRNA binding (Aibara et al 2020;Tobiasson and Amunts 2020). However, only the final stage of the mtLSU assembly with fully mature functional sites has been visualized (Brown et al 2017;Itoh et al 2020), and no preceding steps in the formation have been detected. Therefore, mtLSU assembly remains poorly understood.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Interconnected assembly factors regulate the biogenesis of mitoribosomal large subunit

Tobiasson

Gahura

Aibara

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

AbstractMitoribosomes synthesize essential proteins encoded in the mitochondrial genome. They consist of the ribosomal RNA and protein components, coordinated assembly of which is critical for function. Divergent mitoribosomes with reduced RNA and increased protein mass were described in Trypanosoma brucei, a mammalian parasite causing African Trypanosomiases. Here, we report that the large subunit of T. brucei mitoribosome requires at least 15 biogenesis factors, which we characterized in complex with an assembly intermediate using cryo-EM. These assembly factors form a protein network that spans over 180 Å and connects between functional regions, allowing to coordinate their maturation. The conserved proteins mt-RbgA and mt-EngA are stably bound together at the subunit interface and mitochondrial acyl-carrier proteins play a structural role in constraining the L1 stalk. The characterized assembly intermediate forms an extensive network connecting between functionally important regions of the mitoribosome.Impact statementBiogenesis of Trypanosoma brucei mitoribosomal large subunit requires a protein network of assembly factors that connects between its functional regions.

show abstract

Section: Maturation Of the L7/l12 Stalksupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Interconnected assembly factors regulate the biogenesis of mitoribosomal large subunit

Tobiasson

Gahura

Aibara

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…Moreover, it is also conceivable that mitoribosomes may have acquired a yet unidentified, additional protein to compensate for loss of L1 functionality. Recently, such an additional protein component, mL108, has for example been identified in the L1 stalk of the fungal mitoribosome (preprint: Itoh et al , ).…”

Section: Resultsmentioning

confidence: 99%

Structural insights into mammalian mitochondrial translation elongation catalyzed by mt EFG 1

Kummer

Ban

2020

The EMBO Journal

View full text Add to dashboard Cite

Mitochondria are eukaryotic organelles of bacterial origin where respiration takes place to produce cellular chemical energy. These reactions are catalyzed by the respiratory chain complexes located in the inner mitochondrial membrane. Notably, key components of the respiratory chain complexes are encoded on the mitochondrial chromosome and their expression relies on a dedicated mitochondrial translation machinery. Defects in the mitochondrial gene expression machinery lead to a variety of diseases in humans mostly affecting tissues with high energy demand such as the nervous system, the heart, or the muscles. The mitochondrial translation system has substantially diverged from its bacterial ancestor, including alterations in the mitoribosomal architecture, multiple changes to the set of translation factors and striking reductions in otherwise conserved tRNA elements. Although a number of structures of mitochondrial ribosomes from different species have been determined, our mechanistic understanding of the mitochondrial translation cycle remains largely unexplored. Here, we present two cryo‐EM reconstructions of human mitochondrial elongation factor G1 bound to the mammalian mitochondrial ribosome at two different steps of the tRNA translocation reaction during translation elongation. Our structures explain the mechanism of tRNA and mRNA translocation on the mitoribosome, the regulation of mtEFG1 activity by the ribosomal GTPase‐associated center, and the basis of decreased susceptibility of mtEFG1 to the commonly used antibiotic fusidic acid.

show abstract

“…The data on the first amino acid in the mitoribosome structures were extracted directly from the mmCIF files of PDB entries 6WD0 (Loveland et al, 2020), 5MRC (Desai et al, 2017), 6YWS, 6YW5 (Itoh et al, 2020), 6NU2 (Koripella et al, 2019), 6GAW (Kummer et al, 2018), 6XYW (Waltz et al, 2020), 6HIV (Ramrath et al, 2018), 6ZP1 (Tobiasson & Amunts, 2020) using PDBeCIF (https://pypi.org/ project/PDBeCif/). The number of atoms around each Ca atom were calculated from this data using Python (McKinney, 2010).…”

Section: Discussionmentioning

confidence: 99%

“…While it took many years to solve the first ribosome structures (Ban et al, 2000;Carter et al, 2000;Schluenzen et al, 2000), the progress in cryo-electron microscopy is now rapidly revealing the structural details of mitoribosomes of many different taxonomic groups (Amunts et al, 2015;Desai et al, 2017;Kummer et al, 2018;Ramrath et al, 2018;Itoh et al, 2020;Tobiasson & Amunts, 2020;Waltz et al, 2020). The availability of so many structures highlighted an interesting feature of mitoribosomes-their incredible evolutionary diversity (Waltz & Gieg e, 2019;Kummer & Ban, 2021).…”

Section: Introductionmentioning

confidence: 99%

Widespread use of unconventional targeting signals in mitochondrial ribosome proteins

et al. 2021

View full text Add to dashboard Cite

Mitochondrial ribosomes are complex molecular machines indispensable for respiration. Their assembly involves the import of several dozens of mitochondrial ribosomal proteins (MRPs), encoded in the nuclear genome, into the mitochondrial matrix. Proteomic and structural data as well as computational predictions indicate that up to 25% of yeast MRPs do not have a conventional N-terminal mitochondrial targeting signal (MTS). We experimentally characterized a set of 15 yeast MRPs in vivo and found that five use internal MTSs. Further analysis of a conserved model MRP, Mrp17/bS6m, revealed the identity of the internal targeting signal. Similar to conventional MTS-containing proteins, the internal sequence mediates binding to TOM complexes. The entire sequence of Mrp17 contains positive charges mediating translocation. The fact that these sequence properties could not be reliably predicted by standard methods shows that mitochondrial protein targeting is more versatile than expected. We hypothesize that structural constraints imposed by ribosome assembly interfaces may have disfavored N-terminal presequences and driven the evolution of internal targeting signals in MRPs.

show abstract

Analysis of translating mitoribosome reveals functional characteristics of translation in mitochondria of fungi

Abstract: 18

Cited by 10 publications

References 53 publications

Interconnected assembly factors regulate the biogenesis of mitoribosomal large subunit

Interconnected assembly factors regulate the biogenesis of mitoribosomal large subunit

Structural insights into mammalian mitochondrial translation elongation catalyzed by mt EFG 1

Widespread use of unconventional targeting signals in mitochondrial ribosome proteins

Contact Info

Product

Resources

About