George Church, a genetics professor at Harvard Medical School and member of Harvard’s Origins of Life Initiative, reported the creation of billions of synthetic ribosomes that readily create a long, complex protein called firefly luciferase.
“The reason it is a step toward artificial life is that the key component of all living systems is the ribosome, which does protein synthesis. It is the most conserved and one of the most complicated biological machines,” Church said.
Using the bacteria E. coli, Church and Research Fellow Michael Jewett extracted the bacteria’s natural ribosomes, broke them down into their constituent parts, removed the key ribosomal RNA and then synthesized the ribosomal RNA anew from molecules.
Industry today manufactures proteins on a large scale using natural ribosomes, which evolved over millions of years for natural, not industrial, reasons. Church said that being able to create a ribosome means also being able to tweak it so it better fits industrial needs. One possible use would be to create mirror-image proteins that would be less susceptible to breakdown by enzymes, making them longer-lived.
“You really are in control. It’s like the hood is off and you can tinker directly,” Church said.
Ribosomes are about 20nm (200 Ångström) in diameter and are composed of 65% ribosomal RNA and 35% ribosomal proteins (known as a Ribonucleoprotein or RNP). They translate messenger RNA (mRNA) to build polypeptide chains (e.g., proteins) using amino acids delivered by transfer RNA (tRNA). Their active sites are made of RNA, so ribosomes are now classified as “ribozymes.”
3 million base pairs make up a ribosome
Joining Church at Saturday’s event were human genome pioneer and visiting scholar Craig Venter; Jack Szostak, professor of genetics at Harvard Medical School and Massachusetts General Hospital; George Whitesides, Woodford L. and Ann A. Flowers Professor of Chemistry and Chemical Biology; and Andrew Knoll, Fisher Professor of Natural History and professor of Earth and Planetary Sciences. Harvard Provost Steven E. Hyman introduced the event. It was moderated by professor of astronomy and Origins of Life Director Dimitar Sasselov.
Szostak presented his recent research into the creation and propagation of synthetic cells, showing that membranes form from simple fat molecules spontaneously under certain conditions. In addition to the membranes, he reviewed research into possible ways that basic genetic information may have originally been stored and conveyed in simple RNA-like molecules. His work, he said, is exploring the properties of these RNA-like molecules, seeking variations that make them better early candidates to store and replicate genetic information than either DNA or RNA, which perform those functions in modern cells, but require complex molecular machinery to do so.
In his presentation, Venter described the search for genes around the world, saying that microbes have been found on earth that can withstand radiation levels far beyond that which would be lethal to humans, that can live in corrosive liquids that would eat away a human finger dipped in it, and in a wide array of other environments. The growing library of genes from creatures of all kinds – totaling 50,000 gene families – has created a database from which industry can pick and choose genes for particular applications. Using genetic engineering, synthetic genomes can be created to do such useful things as create clean-burning synthetic fuels, he said.
“I think we’re limited primarily by our own imagination,” Venter said.
This is the same George Church who has a roadmap with three specific technological goals that will enable DNA to be synthesized for a few dollars per kilogram, which would be billions of times cheaper than now.
DNA can be used to create robotics, electronics, molecular structures and can be extended to work with other proteins including hard proteins like keratin which makes horn. Silk and Pyrite (fools gold) are other materials which should work well with and extend from the DNA protein work. DNA has also be used to manipulate gold particles and carbon nanotubes.