The Harvard-led research may have solved the mystery of how life became molecularly right. In the paper, “Origin of biological homology by crystallization of precursor RNA on a magnetic surface,” published in Science advancesresearchers explain how it can all start with the right kind of rock.
Particles can be left-handed, right-handed, or both. RNA and the polysaccharides that make up DNA are right-handed molecules. No one knows why or if there is a reason behind the coincidence that life started right.
By analogy, human hands can be left or right, which are mirror images of each other, meaning they cannot be superimposed without one facing the wrong way. Molecules can have similar structural symmetry.
In the same way that right-handed people have difficulty using left-handed scissors, or left-handed guitar players need to reverse strings and play the instrument in reverse, molecules don’t interact the same way when you’re left or right-handed. Once started, it makes sense that the building blocks of life would continue in the same way.
One interesting idea is that left-handed cosmic rays destroyed left-handed DNA precursors just as life began on Earth.
Ribo-aminooxazoline (RAO) is an important protRNA of two RNA nucleotides, cytosine and uracil. RAO also happens to form a crystal structure that can be either right handed or left handed which once a crystal starts forming, right or left handed, it only bonds to other molecules of the same hand.
By placing RAO on magnetite (Fe3a4), researchers can achieve 100% crystallization of RAO, either left or right, depending on the spin exchange interaction and the degree of spin alignment (magnetization) on the active surface.
Magnetite, the most abundant naturally occurring magnetic mineral on Earth, would have had plenty of opportunities to interact with RAO in primordial times. However, the researchers say the impact is not likely to occur in contact with a particle solution such as clay, but rather on the surfaces of sedimentary rocks.
Even with the current results potentially unlocking two of the four RNA nucleotide components, two more are still missing. So far, the origin story finds that common ingredients that occur naturally at room temperatures can start the process. If the following two were found to have similar requirements, it would indicate that life on any Earth-like planet in the universe could begin just as easily.
S. Furkan Ozturk et al., The origin of biological homology by crystallization of precursor RNA on a magnetic surface, Science advances (2023). DOI: 10.1126/sciadv.adg8274
S. Furkan Ozturk et al., Chiral-induced magnetization of magnetite by precursor RNA, arXiv (2023). doi: 10.48550/arxiv.2304.09095
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