Abstract
Background
The dynamic process of transcription termination produces transient RNA intermediates that are difficult to distinguish from each other via short-read sequencing methods.
Results
Here, we use single-molecule nascent RNA sequencing to characterize the various forms of transient RNAs during termination at genome-wide scale in wildtype Arabidopsis and in atxrn3, fpa, and met1 mutants. Our data reveal a wide range of termination windows among genes, ranging from ~ 50 nt to over 1000 nt. We also observe efficient termination before downstream tRNA genes, suggesting that chromatin structure around the promoter region of tRNA genes may block pol II elongation. 5′ Cleaved readthrough transcription in atxrn3 with delayed termination can run into downstream genes to produce normally spliced and polyadenylated mRNAs in the absence of their own transcription initiation. Consistent with previous reports, we also observe long chimeric transcripts with cryptic splicing in fpa mutant; but loss of CG DNA methylation has no obvious impact on termination in the met1 mutant.
Conclusions
Our method is applicable to establish a comprehensive termination landscape in a broad range of species.
The TATA motif, the CAA motif and the poly(T) transcription termination motif are all important for transcription re-initiation on plant tRNA genes
