EMD-10021

Single-particle
2.97 Å
EMD-10021 Deposition: 03/06/2019
Map released: 03/06/2020
Last modified: 24/04/2024
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links

EMD-10021

Structure of human mitochondrial 28S ribosome in complex with mitochondrial IF3

EMD-10021

Single-particle
2.97 Å
EMD-10021 Deposition: 03/06/2019
Map released: 03/06/2020
Last modified: 24/04/2024
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Sample Organism: Homo sapiens
Sample: IF3 bound mitochondrial translation pre-initiation complex
Fitted models: 6rw4 (Avg. Q-score: 0.599)

Deposition Authors: Itoh Y , Khawaja A
Distinct pre-initiation steps in human mitochondrial translation.
Khawaja A , Itoh Y , Remes C , Spahr H, Yukhnovets O, Hofig H , Amunts A , Rorbach J
(2020) Nat Commun , 11 , 2932 - 2932
PUBMED: 32522994
DOI: doi:10.1038/s41467-020-16503-2
ISSN: 2041-1723
Abstract:
Translation initiation in human mitochondria relies upon specialized mitoribosomes and initiation factors, mtIF2 and mtIF3, which have diverged from their bacterial counterparts. Here we report two distinct mitochondrial pre-initiation assembly steps involving those factors. Single-particle cryo-EM revealed that in the first step, interactions between mitochondria-specific protein mS37 and mtIF3 keep the small mitoribosomal subunit in a conformation favorable for a subsequent accommodation of mtIF2 in the second step. Combination with fluorescence cross-correlation spectroscopy analyses suggests that mtIF3 promotes complex assembly without mRNA or initiator tRNA binding, where exclusion is achieved by the N-terminal and C-terminal domains of mtIF3. Finally, the association of large mitoribosomal subunit is required for initiator tRNA and leaderless mRNA recruitment to form a stable initiation complex. These data reveal fundamental aspects of mammalian protein synthesis that are specific to mitochondria.