Synthesis of human U1 RNA. II. Identification of two regions of the promoter essential for transcription initiation at position +1.
We have analyzed the requirements for human U1 RNA transcription catalyzed by RNA polymerase II. In Xenopus laevis oocytes, a human U1 RNA gene with only 231 and 35 nucleotides of the 5' and 3' flanking regions, respectively (Lund, E. and Dahlberg, J. E. (1984) J. Biol. Chem. 259, 2013-2021), is able to support accumulation of human U1 RNA. We show that the point in the template corresponding to the 5' end of U1 RNA is a site of transcription initiation. That result rules out the possibility that the 5' end of U1 RNA is generated by cleavage and capping of a precursor RNA. The accumulation of correctly initiated human U1 RNA transcripts requires at least two essential upstream elements. The region between positions -231 and -203 is indispensable for transcription both in oocytes and in vitro. The other region, between positions -105 and -6, fixes the location of the 5' ends of the U1 RNA transcripts in oocytes while not altering the overall level of transcription. This latter region contains a sequence located around position -50, which we propose serves as the analog of the T-A-T-A sequence in U1 and U2 RNA genes.
D000818:Animals; D001483:Base Sequence; D004262:DNA Restriction Enzymes; D005260:Female; D005796:Genes; D006801:Humans; D051379:Mice; D009154:Mutation; D009693:Nucleic Acid Hybridization; D009865:Oocytes / Q000201:enzymology*; D009876:Operon; D012313:RNA / Q000235:genetics*; D012319:RNA Polymerase II / Q000378:metabolism*; D012342:RNA, Small Nuclear; D051381:Rats; D013045:Species Specificity; D013698:Templates, Genetic; D014158:Transcription, Genetic; D014981:Xenopus
D012342:RNA, Small Nuclear; D012313:RNA; D012319:RNA Polymerase II; D004262:DNA Restriction Enzymes