So audacious was Marcus Bray’s experiment that even he feared it would fail.
In the system inside cells that translates genetic code into life, he replaced about 1,000 essential linchpins with primitive substitutes to see if the translational system would survive and function. It seemed impossible, yet it worked swimmingly, and Bray had compelling evidence that the great builder of proteins was active in the harsh conditions in which it evolved 4 billion years ago.
The experiment’s success reaffirmed the translational system’s place at the earliest foundations of life on Earth.
Every living thing exists because the translational system receives messages from DNA delivered to it by RNA and translates the messages into proteins. The system centers on a cellular machine called the ribosome, which is made of multiple large molecules of RNA and protein and is ubiquitous in life as we know it.
“There’s nothing alive without ribosomes,” said Loren Williams, a professor at the Georgia Institute of Technology’s School of Chemistry and Biochemistry. “The ribosome is about the oldest and most universal part of biology, and its origins go very far back to a time not too long after Earth had formed and cooled.”
Amazingly, the atomic swaps barely changed the shape of the ribosome.
“It’s totally unbelievable this would work because biology makes very specific use of things. Change one atom and it can wreck a whole protein,” Williams said. “When we probed the structure, we saw that all three metals do essentially the same thing to the structure.”
“Surrounding the ribosome is also a huge cloud of magnesium atoms. It’s called an atmosphere, or shell, and engulfs it completely. I replaced everything, including that, and the whole system still worked.”Paper. (open access) – Marcus S. Bray, Timothy K. Lenz, Jay William Haynes, Jessica C. Bowman, Anton S. Petrov, Amit R. Reddi, Nicholas V. Hud, Loren Dean Williams, Jennifer B. Glass. Multiple prebiotic metals mediate translation. Proceedings of the National Academy of Sciences, 2018; 201803636 DOI: 10.1073/pnas.1803636115 More.
So the system is flexible enough to work despite substitutions of parts.
Note: The “experiment corroborates translational system’s place at earliest foundations of life on Earth”? What are the chances of evolving it randomly by a series of steps? And if that could happen, why isn’t it happening all the time, everywhere (spontaneous generation)?
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See also: Mitochondria have their own ribosomes as well as their own DNA
Ribosome precisely structured for cell growth