Synthetic biology practitioners look at biological life as engineers would look at an ensemble of complex microscopic machines made of biological parts and engines. I recently published a blog post on the Huffington Post scientific section that speaks more in detail exactly about this. If you are interested, you can read it here.
Today, I would like to zoom in on one of those amazing and complex machines: the ribosome. The role of the ribosome within the cell is that of synthesizing proteins: we could as well call it the protein factory. Its structure is very complex, but for our purposes it can be simplified by saying that it is composed of two main parts, namely subunits, made of RNA (ribonucleic acid). To function properly, the ribosome needs the two subunits to come together, as well as the help of some other ancillary proteins.
We can look at the ribosome as a machine able to read the genetic material (as if this was an instruction manual) and to translate it into a protein by putting together different amino acids (which are, in fact, nothing more than the building blocks of proteins). Like a worker would, brick after brick, build a house; the ribosome, amino acid after amino acid, builds a protein.
Proteins are very important big molecules find in every living organism. They have several functions, such as structural components, storage, transport, antibodies, messengers and catalysts for chemical reactions (in this last case they are called enzymes). They are also widely used in many fields of science, such as drug development, biocatalysis (the use of enzymes to perform chemical reactions) and as biosensors, to name a few.
It is, therefore, easy to imagine how the dream of many scientists is to be able to control and engineer the ribosome. In fact, this would mean to have tight control on protein expression (production) and eventually to be able to tune the protein factory to accept amino acids not present in nature to create brand new proteins that could be used as drugs or next generation materials.
In every organism, the two subunits constituting the ribosome are produced separately, and they get together to form an active complex only when the factory needs to be switched on. Until now, scientist believed that the ability of the subunits to freely attach and detach was fundamental for the activity of the ribosome. Sadly, this freedom of the ribosome to exchange subunits at all times also meant limited possibility to engineer the complex as a whole. Every important scientific journal has been speaking about a recent amazing synthetic biology achievement, which was able to overcome just this problem.
A team of scientist from the University of Illinois at Chicago and Northwestern University has been able to create what they have called Ribo-T.
Ribo-T is a complete artificial ribosome in which the two subunits are tethered together and therefore never completely detachable. Imagine the excitement when the team of scientist discovered that the newly engineered ribosome retained its protein synthesis capabilities; not only in vitro but also in vivo! When they substituted the native ribosome with Ribo-T in a living cell, they discovered that Ribo-T can actually carry out the function of its natural counterpart with just a slightly diminished activity (it retains more than half of the activity of the native ribosome). The researchers also proved that it is possible to further engineer the Ribo-T for making it able to accept even unnatural amino acids.
This discovery opens the way to new incredible applications. To be able to engineer the ribosome will allow for a better understanding of the mechanism through which it functions. Not only! Now that the engineering tools are out there, scientists will certainly use them to create different new ribosomes, with great impact on the world of drug discovery and new materials engineering.
Orelle, C., Carlson, E. D., Szal, T., Florin, T., Jewett, M. C., & Mankin, A. S. (2015). Protein synthesis by ribosomes with tethered subunits. Nature, 524(7563), 119–124. http://doi.org/10.1038/nature14862
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