Maximization of selenocysteine tRNA and U6 small nuclear RNA transcriptional activation achieved by flexible utilization of a Staf zinc finger.
Transcriptional activators Staf and Oct-1 play critical roles in the activation of small nuclear RNA (snRNA) and snRNA-type gene transcription. Recently, we established that Staf binding to the human U6 snRNA (hU6) and Xenopus selenocysteine tRNA (xtRNA(Sec)) genes requires different sets of the seven C2-H2 zinc fingers. In this work, using a combination of oocyte microinjection, electrophoretic mobility shift assays, and missing nucleoside experiments with wild-type and mutant promoters, we demonstrate that the hU6 gene requires zinc fingers 2-7 for Staf binding and Oct-1 for maximal transcriptional activity. In contrast, the xtRNA(Sec) gene needs the binding of the seven Staf zinc fingers, but not Oct-1, for optimal transcriptional capacity. Mutation in the binding site for Staf zinc finger 1 in the tRNA(Sec) promoter reduced both Staf binding and transcriptional activity. Conversely, introduction of a zinc finger 1 binding site in the hU6 promoter increased Staf binding but interfered with the simultaneous Staf and Oct-1 binding, thus reducing transcriptional activity. Collectively, these results show that the differential utilization of Staf zinc finger 1 represents a new, critical determinant of the transcriptional activation mechanism for the Xenopus tRNA(Sec) and human U6 snRNA genes.
Schaub
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M
"Structure des Macromolécules Biologiques et Mécanismes de Reconnaissance," UPR 9002 du CNRS, Institut de Biologie Moléculaire et Cellulaire, 15 rue René Descartes, 67084 Strasbourg Cedex, France.
Myslinski
E
E
Krol
A
A
Carbon
P
P
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D004247:DNA / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D051863:Host Cell Factor C1; D006801:Humans; D017665:Hydroxyl Radical / Q000378:metabolism; D008845:Microinjections; D008969:Molecular Sequence Data; D009154:Mutation; D050811:Octamer Transcription Factor-1; D009865:Oocytes; D010446:Peptide Fragments / Q000276:immunology; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012342:RNA, Small Nuclear / Q000235:genetics*; D012345:RNA, Transfer, Amino Acid-Specific / Q000235:genetics*; D017385:Sequence Homology; D013698:Templates, Genetic; D015534:Trans-Activators / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics; D015533:Transcriptional Activation / Q000235:genetics*; D014981:Xenopus; D029867:Xenopus Proteins; D016335:Zinc Fingers / Q000235:genetics*
D004268:DNA-Binding Proteins; C497692:HCFC1 protein, human; D051863:Host Cell Factor C1; D050811:Octamer Transcription Factor-1; C494169:POU2F1 protein, Xenopus; C494165:POU2F1 protein, human; D010446:Peptide Fragments; D012342:RNA, Small Nuclear; D012345:RNA, Transfer, Amino Acid-Specific; D015534:Trans-Activators; D014157:Transcription Factors; D029867:Xenopus Proteins; C114253:ZNF143 protein, human; C036928:tRNA, selenocysteine-; C491943:znf143 protein, Xenopus; D017665:Hydroxyl Radical; D004247:DNA