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Different domains of SNAPc subunits closely interact with U1 versus U6 snRNA gene promoter sequences for differential recruitment of RNA polymerases II and III
Author(s) -
Stumph William E,
Kang Yoon Soon,
Kim Mun Kyoung
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.505.4
Subject(s) - small nuclear rna , biology , rna polymerase ii , polymerase , genetics , rna polymerase iii , base pair , transcription (linguistics) , transcription factor ii d , promoter , rna polymerase , rna polymerase ii holoenzyme , rna , microbiology and biotechnology , gene , rna dependent rna polymerase , gene expression , linguistics , philosophy
The small nuclear RNA activating protein complex (SNAPc) is essential for transcription of genes coding for the spliceosomal snRNAs. In D. melanogaster , the heterotrimeric DmSNAPc recognizes a 21 base‐pair DNA sequence, the PSEA, located approximately 40–60 base pairs upstream of the transcription start site. Upon binding the PSEA, DmSNAPc establishes RNA polymerase II pre‐initiation complexes on U1‐U5 promoters but RNA polymerase III pre‐initiation complexes on U6 promoters. Minor differences in nucleotide sequence of the U1 and U6 PSEAs determine the polymerase specificity; moreover, DmSNAPc adopts different conformations on these two different PSEAs. Such conformational differences in DmSNAPc likely play a key role in establishing the RNA polymerase specificities of the U1 and U6 promoters. We have now determined in some cases that distinct sub‐domains of the DmSNAP50 and DmSNAP43 subunits are differentially in close contact with different nucleotide positions of the U1 and U6 PSEAs. This was established by site‐specific protein‐DNA photocrosslinking combined with site‐specific chemical digestion of the protein. The third subunit, DmSNAP190, has a unique DNA‐binding domain that consists of 4.5 Myb repeats; we are now mapping the architectural arrangement of these Myb repeats on the U1 and U6 PSEAs. (Supported by NSF and in part by the California Metabolic Research Foundation.)