@entity10325 ), a member of the Closteroviridae, has a positive-sense RNA genome of about 20 kb organized into 12 open reading frames (ORFs). The last 10 ORFs are expressed through 3'-coterminal subgenomic RNAs (sgRNAs) regulated in both amounts and timing. Additionally, relatively large amounts of complementary sgRNAs are produced. We have been unable to determine whether these sgRNAs are produced by internal promotion from the full-length template minus strand or by transcription from the minus-stranded sgRNAs. Understanding the regulation of 10 sgRNAs is a conceptual challenge. In analyzing commonalities of a replicase complex in producing so many sgRNAs, we examined initiating nucleotides of the sgRNAs. We mapped the 5' termini of intermediate- (CP and @entity4668 ) and low- ( @entity7818 ) produced sgRNAs that, like the two highly abundant sgRNAs ( @entity9289 and @entity10326 ) previously mapped, all initiate with an @entity1920 . We then examined modifications of the initiation site, which has been shown to be useful in defining mechanisms of sgRNA synthesis. Surprisingly, mutation of the initiating nucleotide of the CTV sgRNAs did not prevent sgRNA accumulation. Based on our results, the CTV replication complex appears to initiate sgRNA synthesis with @entity3042 , preferably with adenylates, and is able to initiate synthesis using a nucleotide a few positions 5' or 3' of the native initiation @entity377 . Furthermore, the context of the initiation site appears to be a regulatory mechanism for levels of sgRNA production. These data do not support either of the established mechanisms for synthesis of sgRNAs, suggesting that CTV sgRNA production utilizes a different mechanism.

Effects of modification of the transcription initiation site context on XXXX subgenomic RNA synthesis.

@entity7818 :: ('100689229', 'Gene') :: ['p18'] @entity3042 :: ('MESH:D011687', 'Chemical') :: ['purines'] @entity1920 :: ('CHEBI:16027', 'Chemical') :: ['adenylate'] @entity377 :: ('CHEBI:36976', 'Chemical') :: ['nucleotide'] @entity4668 :: ('440926', 'Gene') :: ['p13'] @entity10325 :: ('12162', 'Species') :: ['Citrus tristeza virus (CTV'] @entity10326 :: ('10728', 'Gene') :: ['p23'] @entity9289 :: ('51673', 'Gene') :: ['p20']
@entity10325 :: (12162,Species) :: ['citrus tristeza virus']
