Transcriptional Termination Modulated by Nucleotides Outside the Characterized Gene End Sequence of Respiratory Syncytial Virus

Abstract

The genes of respiratory syncytial (RS) virus are transcribed sequentially by the viral RNA polymerase from a single 3'-proximal promoter. Polyadenylation and termination are directed by a sequence at the end of each gene, after which the polymerase crosses an intergenic region and reinitiates at the start sequence of the next gene. The 10 viral genes have different gene end sequences and different termination efficiencies, which allow for regulation of gene expression, since termination of each gene is required for initiation of the downstream gene. RNA sequences within the previously characterized 13 nucleotide gene end, including a conserved sequence 3'-UCAAU-5' and a tract of U residues, are important for termination. In this study, two additional sequence elements outside of the 13 nucleotide gene end were found to modulate termination efficiency: the A residue upstream of the 3'-UCAAU-5' sequence, and the first nucleotide of the intergenic region when it follows a U(4) tract.

Identification of a Single Amino Acid Change in the Human Respiratory Syncytial Virus L Protein That Affects Transcriptional Termination

“…The spacing between the conserved UCAAU and U tract and the length of the U tract were both found to be important for efficient termination (21,44). In addition to the gene end sequence, the composition of the intergenic region was important when the U tract was only four residues (22,44). This finding was similar to results with Simian parainfluenza virus 5 (37,38).…”

“…The semiconserved gene end sequences of HRSV are 13 to 14 nt in length and comprised of a semiconserved A (in 8 of the 10 gene ends) followed by the conserved pentanucleotide 3Ј-UCAAU-5Ј, an A/U-rich central region of one to four nucleotides, and a U tract of four to seven residues (8,22). Thus, an HRSV gene junction is 3Ј-.…”

“…While the effects on termination of the cis-acting genomic sequence elements as well as the trans-acting M2-1 protein have been previously examined, the role of the trans-acting HRSV L protein component of the RdRp complex in transcriptional termination has not been well studied (15,18,19,21,22,32,44). The sequences of L proteins from NNS RNA viruses have been aligned, and six conserved sequence blocks, I to VI, have been identified (35,43,45).…”

Different Temporal Effects of Ebola Virus VP35 and VP24 Proteins on Global Gene Expression in Human Dendritic Cells

“…Even though the gradient of transcription is believed to be universal for nonsegmented negative-strand viruses (50), the levels of transcription of individual genes may not necessarily follow the gradient exactly due to the regulatory role of different elements of gene junctions, which may be different for different pairs of genes. The elements, which effect transcription, include intergenic regions and transcription termination signals, as demonstrated for respiratory syncytial virus (51,52) and recently for EBOV (53). In our study, the abundance of the eGFP mRNA was lower than that of the downstream genes at both time points.…”

Effects of Altering the Transcription Termination Signals of Respiratory Syncytial Virus on Viral Gene Expression and Growth In Vitro and In Vivo

“…Previous studies using dicistronic minigenomes have shown that mutations in any of these three regions can significantly affect the efficiency of transcription termination, though the central region appeared to be the least sensitive (13,22). More recently, it has been suggested that the single nucleotides preceding and following the 12-to 13-nt GE signal also affect the efficiency of termination (12).…”