The biological path leading from genes to proteins is difficult and involves many actors, among which are the ribosomes. These macromolecular assemblies participate in the final stage of protein production, and are thus essential to the survival of our cells. The complex assembly of ribosomes has long been a mystery to researchers. Now, the novel combination of two structural biology techniques makes it possible to unveil our cells’ ingenuity in shaping the ribosomes.

Ribosomes are comprised of proteins and RNA. Through nuclear magnetic resonance (NMR) experiments and small-angle neutron scattering, the researchers have highlighted one of the stages in ribosome construction: the structuring of their RNA. Chemical tags (methyl groups) are grafted one after the other onto specific RNA sites, and give the signal for folding. But the tempo must be respected: the series of events involving these tags are in fact orchestrated by a complex whose 3D structure was deciphered by the biologists. This complex forms pairs of tags and gives them the ‘green light’ to act upon the RNA. According to the researchers, this smooth-running orchestration is necessary for the manufacture of the ribosome and its proper functioning.

The small-angle neutron scattering, which complements the NMR, was performed at the ILL by a researcher from the IBS. This technique involved a novel trick, in which the hydrogen atoms of the observed molecules were cleverly replaced by heavier deuterium atoms, so as to differentiate these molecules from the ones of the solvent in which they are immersed.

In addition to the unprecedented findings on the construction of a ribosome, these experiments open a new field of study for structural biology. The rarely associated NMR and small-angle neutron scattering techniques prove to be complementary and effective for exploring the structures of complex molecular assemblies.

[1] European Molecular Biology Laboratory
[2] Institut Laue-Langevin