Site-specifically arraying small molecules or proteins on DNA using an expanded genetic alphabet.

A class of replicable unnatural DNA base pairs formed between d5SICS and either dMMO2, dDMO, or dNaM were developed. To explore the use of these pairs to produce site-specifically labeled DNA, the synthesis of a variety of derivatives bearing propynyl groups, an analysis of their polymerase-mediated replication, and subsequent site-specific modification of the amplified DNA by Click chemistry is reported. With the d5SICS scaffold a propynyl ether linker is accommodated better than its aliphatic analogue, but not as well as the protected propargyl amine linker explored previously. It was also found that with the dMMO2 and dDMO analogues, the dMMO2 position para to the glycosidic linkage is best suited for linker attachment and that although aliphatic and ether-based linkers are similarly accommodated, the direct attachment of an ethynyl group to the nucleobase core is most well tolerated. To demonstrate the utility of these analogues, a variety of them were used to site-selectively attach a biotin tag to the amplified DNA. Finally, we use d5SICS(CO) -dNaM to couple one or two proteins to amplified DNA, with the double labeled product visualized by atomic force microscopy. The ability to encode the spatial relationships of arrayed molecules in PCR amplifiable DNA should have important applications, ranging from SELEX with functionalities not naturally present in DNA to the production, and perhaps "evolution" of nanomaterials.