The PSEA promoter element of the Drosophila U1 snRNA gene is sufficient to bring DmSNAPc into contact with 20 base pairs of downstream DNA.
Most of the major spliceosomal small nuclear RNAs (snRNAs) (i.e. U1, U2, U4 and U5) are synthesized by RNA polymerase II (pol II). In Drosophila melanogaster, the 5'-flanking DNA of these genes contains two conserved elements: the proximal sequence element A (PSEA) and the proximal sequence element B (PSEB). The PSEA is essential for transcription and is recognized by DmSNAPc, a multi-subunit protein complex. Previous site-specific protein-DNA photo-cross-linking assays demonstrated that one of the subunits of DmSNAPc, DmSNAP43, remains in close contact with the DNA for 20 bp beyond the 3' end of the PSEA, a region that contains the PSEB. The current work demonstrates that mutation of the PSEB does not abolish the cross-linking of DmSNAP43 to the PSEB. Thus the U1 PSEA alone is capable of bringing DmSNAP43 into close contact with this downstream DNA. However, mutation of the PSEB perturbs the cross-linking pattern. In concordance with these findings, PSEB mutations result in a 2- to 4-fold reduction in U1 promoter activity when assayed by transient transfection.
Lai
Hsien-Tsung
HT
Department of Biology, San Diego State University, San Diego, CA 92182-1030, USA.
Chen
Hsiang
H
Li
Cheng
C
McNamara-Schroeder
Kathleen J
KJ
Stumph
William E
WE
D000818:Animals; D020029:Base Pairing; D002478:Cells, Cultured; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics*; D009154:Mutation; D011401:Promoter Regions, Genetic; D012342:RNA, Small Nuclear / Q000235:genetics*; D020218:Response Elements; D016385:TATA Box; D014157:Transcription Factors / Q000378:metabolism*; D015533:Transcriptional Activation
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D012342:RNA, Small Nuclear; D014157:Transcription Factors; C405483:U1 small nuclear RNA; D004247:DNA