Elusive protein factory mapped at last

Victory claimed in race to determine structure of eukaryotic ribosome as many research teams have been striving to determine the structure. But it is significantly larger and more complicated than the bacterial version, and has frustrated many attempts.

The secret, says Adam Ben-Shem of the Institute of Genetics and Molecular and Cellular Biology (IGBMC) in Strasbourg, is that the “ribosome really needs to be handled with gloves of silk”.

The team, working in the lab of Marat Yusupov at the IGBMC, first reduced the level of glucose available to the yeast from which they intended to obtain ribosomes. This inhibited the process of translation, producing a homogeneous population of empty ribosomes.

They then used “very fast and very gentle” purification techniques to obtain ribosome crystals, from which they worked out the structure with X-rays.

The hope is that understanding the ribosome’s structure will lead to a deeper understanding of the basic biology by which the ribosome makes proteins.

Ben-Shem says that “breaking the barrier” of crystallizing a eukaryotic ribosome should open the door to mapping crystal structures from other eukaryotes too, including humans, as well as allowing researchers to study how the ribosome structure changes as it interacts with other molecules during translation.

This yeast structure is the first crystal map of a ribosome in the ‘ratcheted’ state, in which one of the structure’s two subunits is rotated relative to the other, notes Ben-Shem. During translation, RNA is moved along the ribosome as it switches between two states: ratcheted and non-ratcheted.

Studying the ribosome in parasites such as trypanosomes, which cause sleeping sickness among other diseases, and Plasmodium falciparum, which causes malaria, might also lead to the development of drugs that specifically target the ribosome in these organisms.

Via nature

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