Synthesis and use of anti-reverse mrna cap analogues

Abstract

The ability to synthesize capped RNA transcripts in vitro has been of considerable value in a variety of applications. However, one-third to one-half of the caps have, until now, been incorporated in the reverse orientation. Such reverse caps impair the translation of in vitro-synthesized mRNAs. Novel cap analogues, such as P-3'-deoxy-7-methylguanosine-5′P-guanosine-5′triphosphate and P-3′-O,7-dimethylguanosine-5′P-guanosine-5′triphosphate, have been designed that are incapable of being incorporated into RNA in the reverse orientation. Transcripts produced with SP6 polymerase using 'anti-reverse' cap analogues were of the predicted length. Analysis of the transcripts indicated that reverse caps were not formed. The in vitro translational efficiency of transcripts with the novel 'anti-reverse' cap analogues was significantly higher than that of transcripts formed with conventional caps.