Ribosome-building dance

An important step in building ribosomes is like a strictly choreographed dance say scientists from the European Molecular Biology Laboratory (EMBL).

In order to build ribosomes – the cell’s protein factories – other machines have to produce specific RNA molecules, and fold them correctly, before combining them with proteins to form a working ribosome. The cell uses tags called methyl groups to help mark where and how an RNA molecule should be folded, and researchers have discovered that pairs of these tags are added in a specific order

Scientists used nuclear magnetic resonance at EMBL and neutron scattering at the Institut Laue-Langevin (ILL) to determine the 3D structure of the complex that adds methyl tags to the RNA, with the RNA molecules attached. They discovered that the different components of this tagging machine pair up and move in sequence, like dancers following a set choreography.

“We found that the complex has four copies of each protein, and four methylation sites on the RNA, but those methylation sites aren’t all the same,” said Teresa Carlomagno, researcher leader said. “They come in pairs, and one pair has to be methylated before the other.”

The fact that the pairs of tags must be added in a particular sequence could be a means for the cell to control how the RNA is folded, and ultimately when and where ribosomes are formed.

The study – published in Nature - provides a detailed view of the complex in a form that’s very close to what’s found inside our cells. To obtain it, the EMBL scientists teamed up with Frank Gabel at the ILL and the Institut de Biologie Structurale (IBS) to combine their expertise in nuclear magnetic resonance (NMR) with the Gabel lab's skills in small angle neutron scattering (SANS).

The structure of the box C/D enzyme reveals regulation of RNA methylation  http://www.nature.com/nature/journal/vaop/ncurrent/full/nature12581.html