Structural characterization of the gene encoding the large zinc finger protein ZAS3: implication to the origin of multiple promoters in eukaryotic genes.
ZAS3 is a large zinc finger protein that regulates kappaB-mediated transcription and TNF-driven signal transduction pathway. Herein, we have characterized the mouse ZAS3 gene that spans 400 kb and splits into 16 exons. Four ZAS3 exons, ranging from 676 to 3956 nucleotides, are significantly larger than the average size of mammalian internal exons. Intron 10, when retained in mRNAs, encodes N-terminal DNA binding domain, called ZASN. As predicted from cDNAs, 5' untranslated region composed of the 2317 nucleotides is extremely long and contains upstream open reading frames, suggesting that translation initiation of ZAS3 transcripts by conventional cap-dependent ribosome scanning mechanism may be inefficient. Additionally, cDNA data analysis followed by reporter gene assays shows that the ZAS3 locus harbors two promoters that are 80 kb apart. The data suggest that the expression of ZAS3 is controlled by a combination of differential promoter usage, alternative splicing, and possible intergenic splicing. The distribution and degree of conservation of exons within the ZAS3 locus, together with the complex alternative splicing events and upstream open reading frame in 5' untranslated exons, lead us to speculate that multiple promoters of an eukaryotic gene might be residual traces of regulatory regions of other genes lost in evolution.
Hong
Joung-Woo
JW
Department of Molecular and Cellular Biochemistry, The Ohio State University, College of Medicine and Public Health, Columbus, OH 43210, USA.
Wu
Lai-Chu
LC
D020121:5' Untranslated Regions; D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics*; D030541:Databases, Genetic; D004792:Enzyme Precursors / Q000235:genetics; D005091:Exons; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D007438:Introns; D051379:Mice; D008969:Molecular Sequence Data; D009954:Ornithine Carbamoyltransferase / Q000235:genetics; D011401:Promoter Regions, Genetic; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics*
D020121:5' Untranslated Regions; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D004792:Enzyme Precursors; D014157:Transcription Factors; C497203:ZAS3 protein, mouse; C414168:pre-ornithine transcarbamoylase; D009954:Ornithine Carbamoyltransferase