O-67 - All BsaI-BsmBI-site differences from RaTG13-BANAL-52 are silent, at an elevated rate
All 12 nucleotide differences at BsaI/BsmBI sites between RaTG13 and SARS-CoV-2, and all 5 between BANAL-52 and SARS-CoV-2, are synonymous (silent); the rate of silent mutations within these recognition sites is significantly higher than across the rest of the genome (RaTG13 OR=8.9, P=9e-8; BANAL-52 OR=5.2, P=0.004).
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Why this is evidence
Restriction-site differences from RaTG13/BANAL-52 being exclusively silent, at a significantly elevated rate, is the signature of deliberate site editing that preserves the protein — favouring H-43 over the natural members.