Facile synthesis of nucleoside 5′-(α-P-seleno)-triphosphates and phosphoroselenoate RNA transcription

Phosphoroselenoate RNA (PSe-RNA) is nuclease resistant and has great potentials in X-ray crystal structure and function studies of noncoding RNAs and protein-RNA interactions. In order to conveniently synthesize PSe-RNA via transcription, we have developed a one-pot synthetic method for the nucleoside 5′-(α-P-seleno)-triphosphates (NTPaSe) analogs without protecting any functionality of the ribonucleosides. The NTPaSe diastereomers have been purified, fully characterized, and incorporated into RNAs by T7 RNA polymerase. The transcribed RNAs are diastereomerically pure, and the Se-derivatized ribozymes are generally active. Furthermore, we have established an affinity purification strategy by using immobilized boronate to conveniently purify NTPαSe analogs. Though the affinity-purified NTPαSe analogs are diastereomeric mixtures, they can be directly used in transcription without a significant impact on the transcription efficiency. Moreover, we found that the PSenucleotide is stable during polyacrylamide gel purification, indicating that the PSe-RNAs can be purified straightforwardly for crystal structural and functional studies.