13 februari 2019

Molecular basis for the variability of mitoribosomes revealed

Ragnarforskaren Alexey Amunts är en av författarna till publikationen "Structural Patching Fosters Divergence of Mitochondrial Ribosomes"*.

Mitochondrial ribosomes are known to be highly variable across species, but the molecular basis for this phenomenon was not known. The analysis published in Molecular Biology and Evolution uncover a fundamental evolutionary mechanism that drives the increasing diversity. The interdisciplinary study was led by Alexey Amunts in collaboration with researchers from Georgia Institute of Technology and Harvard Medical School. 

Despite a common ancestry, mitoribosomes are morphologically diverse and vary in protein and rRNA content in different species. Previous work from Amunts and colleagues showed that even defining functional features of mitoribosomes have been affected. The diversity of mitoribosomes is unprecedented in other homologous systems, and the structures of their cytosolic counterparts from different species are highly similar. By combining three-dimensional structural information with a comparative analysis of the secondary structures of mitochondrial rRNAs and available proteomic data, the researchers generated a map of variations and reconstructed the fundamental stages that shaped the evolution of mitoribosomes. The analysis suggests that rapidly evolving mitochondrial rRNA causes structural instabilities in mitoribosomes that are patched by acquisition of pre-existing compensatory elements. Since the toolkits of elements utilized for structural patching differ between mitochondria of different species, it fosters the growing divergence of mitoribosomes. This molecular mechanism underlies the incorporation of the mt-tRNA into the human mitoribosome, and the altered path of the exit tunnel in yeast mitoribosome.


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* (Anton S Petrov, Elizabeth C Wood, Chad R Bernier, Ashlyn M Norris, Alan Brown, Alexey Amunts)