title: Site-directed mutational analysis of a U4 small nuclear RNA gene proximal sequence element. Localization and identification of functional nucleotides.
abstract: The genes that encode the small nuclear RNAs (snRNAs) are unusual RNA polymerase II transcription units in that 5'-flanking DNA sequences more than 50 base pairs upstream of snRNA genes are essential for specifying the transcription initiation site. The relevant cis-acting DNA sequence, termed the proximal sequence element (PSE), is required for both transcription initiation and 3'-end formation of snRNAs. We have used site-directed mutagenesis and expression in Xenopus oocytes to map nucleotides important for the function of the chicken U4B snRNA gene PSE. The results indicate that nucleotide sequences upstream of position -65 are not required for U4B PSE activity. However, nucleotides lying within a region 53-65 base pairs upstream of the U4B gene are essential for obtaining a detectable level of U4B gene expression. Six nucleotides between positions -53 and -59 were identified at which base substitutions reduced the transcriptional activity of the U4B gene.
authors.affiliation: Department of Chemistry, San Diego State University, California 92182-0328.
authors.forename: K J
authors.initials: KJ
authors.lastname: McNamara
authors.forename: W E
authors.initials: WE
authors.lastname: Stumph
mesh_terms: D000818:Animals; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D002645:Chickens; D003001:Cloning, Molecular; D005260:Female; D005796:Genes; D008969:Molecular Sequence Data; D009154:Mutation; D009865:Oocytes / Q000378:metabolism; D012319:RNA Polymerase II / Q000378:metabolism; D012342:RNA, Small Nuclear / Q000235:genetics*; D015183:Restriction Mapping; D013698:Templates, Genetic; D014158:Transcription, Genetic; D014982:Xenopus laevis
chemical_list: D012342:RNA, Small Nuclear; D012319:RNA Polymerase II