title: Blocking of Tat-dependent HIV-1 RNA modification by an inhibitor of RNA polymerase II processivity.
abstract: Human immunodeficiency virus gene expression is regulated transcriptionally and post-transcriptionally by the virally encoded tat protein (Tat). Tat functions through an RNA target sequence located in the untranslated region at the 5' end of viral transcripts. In Xenopus oocytes, translation of RNA containing the target sequence is specifically activated by Tat. This activation only occurs if the RNA is injected into the nucleus, and might be due to Tat-dependent, nucleus-specific chemical modification of the RNA which somehow facilitates translation. Here we demonstrate that Tat activation of its target RNA in the nucleus involves a Tat-dependent covalent modification. The modified RNA is competent for translation after reinjection into either the nucleus or the cytoplasm in the absence of Tat. Furthermore, we find that the nucleoside analogue 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole, which inhibits processivity of RNA polymerase II (ref. 9), blocks this Tat-dependent modification.
authors.affiliation: Virus Molecular Biology Group, Department of Biochemistry, Oxford, UK.
authors.forename: M
authors.initials: M
authors.lastname: Braddock
authors.forename: A M
authors.initials: AM
authors.lastname: Thorburn
authors.forename: A J
authors.initials: AJ
authors.lastname: Kingsman
authors.forename: S M
authors.initials: SM
authors.lastname: Kingsman
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004004:Dichlororibofuranosylbenzimidazole / Q000494:pharmacology; D015696:Gene Products, tat / Q000378:metabolism*; D015497:HIV-1 / Q000235:genetics*; D066298:In Vitro Techniques; D014176:Protein Biosynthesis; D012319:RNA Polymerase II / Q000037:antagonists & inhibitors*; D012333:RNA, Messenger / Q000235:genetics; D012367:RNA, Viral / Q000378:metabolism*; D012045:Regulatory Sequences, Nucleic Acid; D014982:Xenopus laevis; D054322:tat Gene Products, Human Immunodeficiency Virus
chemical_list: D015696:Gene Products, tat; D012333:RNA, Messenger; D012367:RNA, Viral; D054322:tat Gene Products, Human Immunodeficiency Virus; D004004:Dichlororibofuranosylbenzimidazole; D012319:RNA Polymerase II