Can the RNA World Still Function without Cytidine

摘要: Most scenarios for the origin of life assume that RNA played a key role in both catalysis and information storage. The A, U, G, C nucleobases modern all participate secondary structure formation replication. However, rapid deamination to U absence meteorite samples suggest prebiotic may have been deficient cytosine. Here, we assess ability sequences formed from three-letter AUG alphabet perform structural genetic roles comparison AUGC alphabet. Despite forming less thermodynamically stable helices, can find broad range structures thus appears sufficient World. case, longer are required form with an equivalent complexity. Replication requires GU pairing. Sequence fidelity is low whenever G's present sequence. We evolve AU if pairing rare, RU common (R denotes A or G). It not possible conserve G at specific site either case. These problems do rule out possibility World based on AUG, but they show it wouldbe significantly more difficult than four-base