Staf, a novel zinc finger protein that activates the RNA polymerase III promoter of the selenocysteine tRNA gene.
The selenocysteine tRNA gene (tRNA(Sec)) is atypical. Though transcribed by RNA polymerase III like all other tRNA genes, its basal promoter elements are distinct and reside essentially upstream of the coding region. In addition, transcription from the basal promoter is activated by a 15 bp activator element. In this report we describe the cloning and functional characterization of Staf (selenocysteine tRNA gene transcription activating factor), a novel Xenopus laevis transcription factor which binds to the tRNA(Sec) activator element and mediates its activation properties. The 600 amino acid Staf protein contains seven zinc fingers and a separate acidic activation domain. Seven highly conserved regions were detected between Staf and human ZNF76, a protein of unknown function, thereby aiding in predicting the locations of the functional domains of Staf. With the use of a novel expression assay in X.laevis oocytes we succeeded in demonstrating that Staf can activate the RNA polymerase III promoter of the tRNA(Sec) gene. This constitutes the first demonstration of the capacity of a cloned factor to activate RNA polymerase III transcription in vivo.
Schuster
C
C
UPR 9002 du CNRS Structure des Macromolécules Biologiques et Mécanismes de Reconnaissance, IBMC, Strasbourg, France.
Myslinski
E
E
Krol
A
A
Carbon
P
P
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D017930:Genes, Reporter; D006801:Humans; D008969:Molecular Sequence Data; D009865:Oocytes; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012320:RNA Polymerase III / Q000235:genetics*; D012333:RNA, Messenger; D012345:RNA, Transfer, Amino Acid-Specific / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000502:physiology*; D029867:Xenopus Proteins; D014982:Xenopus laevis; D016335:Zinc Fingers
D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D012345:RNA, Transfer, Amino Acid-Specific; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D029867:Xenopus Proteins; C114253:ZNF143 protein, human; C036928:tRNA, selenocysteine-; C491943:znf143 protein, Xenopus; D004247:DNA; D012320:RNA Polymerase III