Ученые пересмотрели порядок появления аминокислот в генетическом коде

Here’s what you’ll learn when you read this story: - A peer-reviewed analysis challenged the familiar order in which the 20 canonical amino acids were recruited into the genetic code. - The last universal common ancestor, or LUCA, is the ancient organism—or population of organisms—from which all known life descends. - New research says amino acids may have come from several abiotic routes, and engineered cells suggest some core biological machinery can function with a reduced amino-acid alphabet. Scientists are making a case for adjusting one very old piece of biology: the order in which amino acids became part of the genetic code. For years, researchers have worked with a rough chronology for how those molecular building blocks entered life’s translation machinery. But according to a University of Arizona-led 2024 analysis published in Proceedings of the National Academy of Sciences, that familiar order may lean too heavily on later biology and on classic prebiotic chemistry experiments rather than on traces left in ancient protein domains. Since that analysis, new papers from 2026 have widened the possible sources of prebiotic amino acids, strengthened some mineral-and-seafloor chemistry scenarios, and shown that engineered core cellular machinery can survive with one fewer amino acid. While we didn’t “solve” the origin of life, this means our current working model of gene history could be undervaluing early protolife (which included forerunners like RNA and peptides), as compared to what emerged with and after the beginning of life. Our understanding of these extremely ancient times will always be incomplete, but it’s important for us to keep researching early Earth. The scientists explain that any improvements in that understanding could not only allow us to know more of our own story, but also help us search for the beginnings of life elsewhere in the universe. In the 2024 PNAS paper, researchers led by senior author Joanna Masel and first author Sawsan Wehbi explain that vital pieces of our proteins (a.k.a. amino acids) date back four billion years—to the last universal common ancestor (LUCA) of all life on Earth. These chains of dozens or more amino acids, called protein domains, are “like a wheel” on a car, Wehbi said in a statement: “It’s a part that can be used in many different cars, and wheels have been around much longer than cars.” The group used specialized software and National Center for Biotechnology Information data to build an evolutionary (so to speak) tree of these protein domains, which were not theorized or observed until the 1970s. Our knowledge of these details has grown by leaps and bounds. The “where did the amino acids come from?” side of the story has also spread out. In February 2026, a PNAS paper based on OSIRIS-REx Bennu samples argued that amino acids in the early Solar System did not come from one neat chemical pathway. The isotopic evidence pointed one way for glycine in the Murchison meteorite—mainly Strecker-like aqueous chemistry—and another way for glycine in Bennu, where modified radical–radical reactions in cold primordial ices looked more important. In a separate Nature Communications paper, published in April 2026, researchers found that common carbonate and phyllosilicate minerals carrying trace transition-metal cations can catalyze geoelectrochemical CO2 reduction, producing methane, formic acid, carbon monoxide, C2 organics, and some carbon-nitrogen compounds. So, how do we rethink the order in which the 20 essential genetic amino acids emerged from the stew of early Earth? The University of Arizona scientists argue that the current model overemphasizes how often an amino acid appeared in an early life form, leading to a theory that the amino acid found in the highest saturation must have emerged first. This folds into existing research, like a 2017 paper suggesting that our amino acids represent the best of the best, not just a “frozen accident” of circumstances. In the paper, the scientists say that amino acids could have even come from different portions of young Earth, rather than from the entire thing as a uniform environment. Synthetic biology has now given that staged-code idea a strange little stress test. In an April 30 2026 Science paper, researchers redesigned essential E. coli ribosomal proteins to remove isoleucine, replaced all 382 isoleucine residues in the ribosome, and combined 21 redesigned ribosomal subunits at a native genomic locus. The result was a viable, evolutionarily stable engineered cell. While that cell wasn’t a fossil or a model of early Earth, it showed that at least some core cellular machinery can keep working with a reduced amino-acid alphabet, which makes stripped-down or transitional coding systems feel less like pure chalkboard biology. Tryptophan, designated W, was the showiest part of the 2024 PNAS result because scientists have generally treated it as one of the last canonical amino acids to join the genetic code. “[T]here is scientific consensus that W was the last of the 20 canonical amino acids to be added to the genetic code,” the scientists wrote. But in their reconstruction, they found 1.2 percent W in the pre-LUCA data and 0.9 percent after LUCA. That is a small absolute difference, but a 25 percent relative drop. In a May 2026 bioRxiv preprint, revised in June, Wehbi and colleagues returned to tryptophan from a different angle: the structural phylogenetics of tryptophanyl-tRNA synthetase and tyrosyl-tRNA synthetase. They argued that tryptophan usage may have originated in Bacteria, appeared later in Archaea, and moved toward universality through horizontal gene transfer. If that interpretation holds, the last step that made tryptophan universal may have happened after LUCA. Why would the last amino acid to emerge be more common before the branching of all resulting life? The team theorized that the chemical explanation might point to an even older version of the idea of genetics. As in all things evolutionary, there’s no intuitive reason why any one successful thing must be the only of its kind or family to ever exist. “Stepwise construction of the current code and competition among ancient codes could have occurred simultaneously,” the scientists conclude. And, tantalizingly, “[a]ncient codes might also have used noncanonical amino acids.” These could have emerged around the alkaline hydrothermal vents that are believed to play a key role in how life began, despite the fact that the resulting life forms did not live there for long. To apply this theory to the rest of the universe, we don’t have to go far, either. “[A]biotic synthesis of aromatic amino acids might be possible in the water–rock interface of Enceladus’s subsurface ocean,” the Arizona scientists explained in 2024. That’s a good reason to keep watching Saturn’s icy moon. A Nature Astronomy paper from earlier this year argued that the statistical organization of amino-acid and fatty-acid assemblages may distinguish biotic from abiotic samples better than single molecules alone. Another paper using Enceladus as a case study, also in Nature Astronomy, concluded that uncertainties in abiotic chemistry could keep future amino-acid-chirality and methane-isotope measurements from definitively proving a biosphere unless scientists also understand the moon’s geophysics, organic inventory, and transport processes. Caroline Delbert is a writer, avid reader, and contributing editor at Pop Mech. She's also an enthusiast of just about everything. Her favorite topics include nuclear energy, cosmology, math of everyday things, and the philosophy of it all.