title: Architectural arrangement of the small nuclear RNA (snRNA)-activating protein complex 190 subunit (SNAP190) on U1 snRNA gene promoter DNA.
abstract: Myb repeats ∼52 amino acid residues in length were first characterized in the oncogenic Myb transcription factor, which contains three tandem Myb repeats in its DNA-binding domain. Proteins of this family normally contain either one, two, or three tandem Myb repeats that are involved in protein-DNA interactions. The small nuclear RNA (snRNA)-activating protein complex (SNAPc) is a heterotrimeric transcription factor that is required for expression of small nuclear RNA genes. This complex binds to an essential promoter element, the proximal sequence element, centered ∼50 base pairs upstream of the transcription start site of snRNA genes. SNAP190, the largest subunit of SNAPc, uncharacteristically contains 4.5 tandem Myb repeats. Little is known about the arrangement of the Myb repeats in the SNAPc-DNA complex, and it has not been clear whether all 4.5 Myb repeats contact the DNA. By using a site-specific protein-DNA photo-cross-linking assay, we have now mapped specific nucleotides where each of the Myb repeats of Drosophila melanogaster SNAP190 interacts with a U1 snRNA gene proximal sequence element. The results reveal the topological arrangement of the 4.5 SNAP190 Myb repeats relative to the DNA and to each other when SNAP190 is bound to a U1 promoter as a subunit of SNAPc.
authors.affiliation: Molecular Biology Institute and the Department of Biology, San Diego State University, San Diego, California 92182-1030, USA.
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Doherty
authors.forename: Yoon Soon
authors.initials: YS
authors.lastname: Kang
authors.forename: Cheryn
authors.initials: C
authors.lastname: Lee
authors.forename: William E
authors.initials: WE
authors.lastname: Stumph
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster; D017434:Protein Structure, Tertiary; D020598:Proto-Oncogene Proteins c-myb / Q000235:genetics / Q000378:metabolism*; D012342:RNA, Small Nuclear / Q000096:biosynthesis* / Q000235:genetics; D020449:Repetitive Sequences, Amino Acid; D020218:Response Elements / Q000502:physiology*
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C467519:Myb protein, Drosophila; C534010:Pbp95 protein, Drosophila; D020598:Proto-Oncogene Proteins c-myb; D012342:RNA, Small Nuclear; C405483:U1 small nuclear RNA; D004247:DNA