The PolyA tail length of yeast histone mRNAs varies during the cell cycle and is influenced by Sen1p and Rrp6p

Yeast histone mRNAs are polyadenylated, yet factors such as Rrp6p and Trf4p, required for the 3'-end processing of non-polyadenylated RNAs, contribute to the cell cycle regulation of these transcripts. Here, we investigated the role of other known 3'-end processing/transcription termination factors of non-polyadenylated RNA in the biogenesis of histone mRNAs, specifically the Nab3p/Nrd1p/Sen1p complex. We also re-evaluated the polyadenylation status of these mRNAs during the cell cycle. Our analysis reveals that yeast histone mRNAs have shorter than average PolyA tails and the length of the PolyA tail varies during the cell cycle; S-phase histone mRNAs possess very short PolyA tails while in G1, the tail length is relatively longer. Inactivation of either Sen1p or Rrp6p leads to a decrease in the PolyA tail length of histone mRNAs. Our data also show that Sen1p contributes to 3'-end processing of histone primary transcripts. Thus, histone mRNAs are distinct from the general pool of yeast mRNAs and 3'-end processing and polyadenylation contribute to the cell cycle regulation of these transcripts.