Cascade of reduced speed and accuracy after errors in enzyme-free copying of nucleic acid sequences.

Nonenzymatic, template-directed synthesis of nucleic acids is a paradigm for self-replicating systems. The evolutionary dynamics of such systems depend on several factors, including the mutation rates, relative replication rates, and sequence characteristics of mutant sequences. We measured the kinetics of correct and incorrect monomer insertion downstream of a primer-template mismatch (mutation), using a range of backbone structures (RNA, DNA, and LNA templates and RNA and DNA primers) and two types of 5′-activated nucleotides (oxyazabenzotriazolides and imidazolides, i.e., nucleoside 5′-phosphorimidazolides). Our study indicated that for all systems studied, an initial mismatch was likely to be followed by another error (54–75% of the time), and extension after a single mismatch was generally 10–100 times slower than extension without errors. If the mismatch was followed by a matched base pair, the extension rate recovered to nearly normal levels. On the basis of these data, we simulated nucleic acid re...