A roadmap for ribosome assembly in human mitochondria.

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Mitochondria utilize mitoribosomes for synthesizing core oxidative phosphorylation components.
• Mitoribosome biogenesis is complex, involving nuclear and mitochondrial genomes and dedicated assembly factors.
• Defects in mitoribosome assembly are linked to severe human diseases, but the pathway is poorly understood.

Purpose of the Study:

• To elucidate the molecular pathway of human mitoribosome assembly.
• To provide a comprehensive roadmap of mitoribosome biogenesis from early to late stages.

Main Methods:

• Employed a multidisciplinary approach combining biochemical isolation of native mitoribosomal assembly complexes.
• Utilized quantitative mass spectrometry and mathematical modeling to reconstitute the assembly pathway.
• Analyzed ribosomal protein-only modules and their assembly onto ribosomal RNA.

Main Results:

• Demonstrated that human mitoribosome biogenesis involves distinct protein-only modules, differing from bacterial and cytosolic counterparts.
• Showed these modules assemble onto ribosomal RNA in a coordinated manner.
• Identified excess protein-only modules as a strategy for efficient assembly of the dual-genome-derived complex.

Conclusions:

• Human mitoribosome assembly follows a unique pathway characterized by protein-only module formation.
• This pathway facilitates the efficient construction of protein-rich ribonucleoprotein complexes from dual genetic origins.
• The study highlights evolutionary divergence in ribosome biogenesis compared to bacterial ancestors.