Abstract
The paramyxovirus genome, a nonsegmented, negative-polarity, single-stranded RNA of approximately 15 kb, contains six transcription units flanked at the 3' and 5' ends by a short (approximately 50- to 60-nucleotide) extracistronic sequence, dubbed the positive and negative leader regions. These leader template regions, present at the 3' end of the genome and the antigenome, have been shown to contain essential signals governing RNA replication activity. Whether they are sufficient to promote replication is still open to question. By using a series of Sendai virus defective interfering RNAs carrying a nested set of deletions in the promoter regions, it is shown here that for both the genomic and antigenomic promoters, a 3'-end RNA sequence of 96 nucleotides is required to allow replication. Sequence comparison of active and inactive promoters led to the identification of a set of three nucleotide hexamers (nucleotides 79 to 84, 85 to 90, and 91 to 96) containing a repeated motif RXXYXX [shown as 5'-3' positive-strand]. Sequential mutation of each hexamer into its complementary sequence confirmed their essential role. The three hexamers are required, and their relative positioning is important, since displacing them by 6 nucleotides destroyed promoter function. RNAs carrying degenerate nucleotides in the three hexamers were used as replication templates. They led to the selection of actively replicating RNA species exclusively carrying the basic motif (GNNNNN)3 from nucleotides 79 to 96. These results clearly show that, apart from the region from nucleotides 1 to 31, previously identified as governing Sendai virus replication activity, a second element, spanning at the most nucleotides 79 to 96, appears essential. Thus, the paramyxovirus replication promoters are not confined to the leader template regions, as seems to be the case for the rhabdoviruses.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
