Recognition of threosyl nucleotides by DNA and RNA polymerases.

Alpha-L-threose nucleic acids (TNA) are potentially natural nucleic acids that could have acted as an evolutionary alternative to RNA. We determined whether DNA or RNA polymerases could recognize phosphorylated threosyl nucleosides. We found that for both the Vent (exo-) DNA polymerase and HIV reverse transcriptase K(m) values were increased and kcat values decreased for the incorporation of tTTP in comparison to their natural counterparts. Our results suggest that TNA may have played a role in the evolution of the DNA-RNA-protein world. Thus, TNA may be a candidate for further studies in evolutionary chemistry and biology.