2',5'-linked DNA is a template for polymerase-directed DNA synthesis.
Genomes are composed of nucleic acids bearing 3',5'-phosphodiester-linked sugars. The 2',5'-phosphodiester linkage is a fundamental alternative to the natural linkage and is the predominant product of most nontemplate, nonenzymatic oligomerizations of nucleotide monomers. This fact suggests a chemical bias for the formation of 2',5'-phosphodiester bonds, an important consideration in the context of molecular evolution on Earth or elsewhere. Although 2',5'-linked RNA occurs naturally, it is evidently not used to encode genetic information. Nevertheless, the capacity of the 2',5'-phosphodiester linkage to serve as a genetic material has been probed in laboratory experiments. Initial studies examined both self-pairing and pairing with natural nucleic acids. These studies showed that, while 2',5'-linked DNA and RNA form double and triple helices with themselves, their interactions with natural nucleic acids are asymmetric-pairing is seen with 3',5'-linked RNA but not DNA. Although the ability to form a stable structure (such as a helix) is likely a necessary condition for nonenzymatic information transfer, in the case of enzymatic reactions this precondition may be expected to be lifted in cases where the enzyme can serve as a "template for the template" and make up for structural deficiencies that would be fatal to its abiotic counterpart. In support of this suggestion, we demonstrate that 2',5'-linked DNA is a template for enzymatic synthesis of natural DNA with a variety of DNA polymerases and reverse transcriptases directing the incorporation of all four natural nucleotides with fidelity.
Sinha
Surajit
S
Department of Chemistry, University of California-Riverside, Riverside, California 92521, USA.
Kim
Paul H
PH
Switzer
Christopher
C
D004247:DNA / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D004256:DNA Polymerase I / Q000378:metabolism*; D009690:Nucleic Acid Conformation; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism*; D013698:Templates, Genetic
D004247:DNA; D012194:RNA-Directed DNA Polymerase; D004256:DNA Polymerase I