Formation and metabolism of histone mRNAs with mutant 3' ends formed by snRNA termination signals.

ABSTRACT

Histone mRNAs are the only non-polyadenylated mRNAs, ending in a conserved 26 nt sequence which can form a stem-loop. It has not been possible to make histone mRNAs with mutant stem-loops since most mutations in the stem-loop interfere with the 3' processing reaction. The snRNA genes transcribed by RNA polymerase II form their 3' ends by transcription termination directed by a signal which is located entirely 3' of the snRNA coding sequence. Chimeric genes which express RNAs ending in a histone 3' end or in mutant histone 3' ends formed by snRNA termination signals were constructed. The mRNAs from these genes were efficiently transported from the nucleus after injection of the genes into frog oocytes. This was true even for RNAs which end in mutant stem-loops suggesting that the snRNA termination signals promote transport of the transcripts.