What is it about?
The order in which the amino acids were added to the genetic code was previously inferred from consensus among forty metrics. Many of these reflect how easily the amino acids can be made in the absence of life. However, the genetic code arose to use amino acids in living cells that already relied on sophisticated RNA and peptides. Here, we directly infer the order of recruitment from how often each amino acid is used in the most ancient protein sequences, compared to somewhat less ancient sequences. Small amino acid size predicts ancient enrichment better than the previous consensus metric does. We place metal-binding and sulfur-containing amino acids earlier than previously thought, highlighting the importance of metal-dependent catalysis and sulfur metabolism to ancient life. The most ancient proteins are also surprisingly enriched for amino acids whose chemical structures contain rings.
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Why is it important?
Understanding early life has implications for our search for life elsewhere in the universe.
Read the Original
This page is a summary of: Order of amino acid recruitment into the genetic code resolved by last universal common ancestor’s protein domains, Proceedings of the National Academy of Sciences, December 2024, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2410311121.
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