7PO0

Assembly intermediate of human mitochondrial ribosome small subunit without mS37 in complex with RBFA and IF3

This is a non-PDB format compatible entry.

Summary for 7PO0

• Entry DOI: 10.2210/pdb7po0/pdb
• EMDB information: 13558
• Descriptor: 12S mitochondrial rRNA, 28S ribosomal protein S12, mitochondrial, 28S ribosomal protein S14, mitochondrial, ... (40 entities in total)
• Functional Keywords: small subunit, mitochondrion, ribosome
• Biological source: Homo sapiens (Human); More
• Total number of polymer chains: 32
• Total formula weight: 1203064.42

Authors

Itoh, Y.,Khawaja, A.,Rorbach, J.,Amunts, A. (deposition date: 2021-09-08, release date: 2022-06-15, Last modification date: 2024-04-24)

Primary citation

Itoh, Y.,Khawaja, A.,Laptev, I.,Cipullo, M.,Atanassov, I.,Sergiev, P.,Rorbach, J.,Amunts, A.
Mechanism of mitoribosomal small subunit biogenesis and preinitiation.
Nature, 606:603-608, 2022

PubMed Abstract: Mitoribosomes are essential for the synthesis and maintenance of bioenergetic proteins. Here we use cryo-electron microscopy to determine a series of the small mitoribosomal subunit (SSU) intermediates in complex with auxiliary factors, revealing a sequential assembly mechanism. The methyltransferase TFB1M binds to partially unfolded rRNA h45 that is promoted by RBFA, while the mRNA channel is blocked. This enables binding of METTL15 that promotes further rRNA maturation and a large conformational change of RBFA. The new conformation allows initiation factor mtIF3 to already occupy the subunit interface during the assembly. Finally, the mitochondria-specific ribosomal protein mS37 (ref. ) outcompetes RBFA to complete the assembly with the SSU-mS37-mtIF3 complex that proceeds towards mtIF2 binding and translation initiation. Our results explain how the action of step-specific factors modulate the dynamic assembly of the SSU, and adaptation of a unique protein, mS37, links the assembly to initiation to establish the catalytic human mitoribosome.

PubMed: 35676484
DOI: 10.1038/s41586-022-04795-x

Experimental method

ELECTRON MICROSCOPY (2.9 Å)