title: Mutational analysis of the rous sarcoma virus DR posttranscriptional control element.
abstract: The direct repeat (DR) sequences flanking the src gene in Rous sarcoma virus are essential posttranscriptional control elements; at least one copy of this sequence is necessary for cytoplasmic accumulation of unspliced viral RNA. These sequences promote Rev-independent human immunodeficiency virus type 1 expression, suggesting they act as constitutive transport elements (CTEs). To determine which regions of this sequence are critical for CTE function, mutations in the downstream DR were generated and tested in a viral deletion construct lacking src and the upstream DR. Two single-point mutations and three different clustered mutations caused substantial reductions in reverse transcriptase activity, Gag protein levels, and unspliced viral RNA in the cytoplasm. Three conserved regions of the CTE, including nucleotides 8844 to 8847, 8862 to 8864, and 8868 to 8870, were most sensitive to inactivation by mutagenesis.
authors.affiliation: Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: R A
authors.initials: RA
authors.lastname: Ogert
authors.forename: K L
authors.initials: KL
authors.lastname: Beemon
mesh_terms: D000818:Animals; D001358:Avian Sarcoma Viruses / Q000235:genetics*; D001483:Base Sequence; D003593:Cytoplasm / Q000378:metabolism; D004252:DNA Mutational Analysis; D015683:Gene Products, gag / Q000096:biosynthesis; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017354:Point Mutation; D012326:RNA Splicing; D012367:RNA, Viral; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D012091:Repetitive Sequences, Nucleic Acid; D014771:Virion
chemical_list: D015683:Gene Products, gag; D012367:RNA, Viral; D012194:RNA-Directed DNA Polymerase