Optimal tRNA((Ser)Sec) gene activity requires an upstream SPH motif.
The X. laevis tRNA((Ser)Sec) gene is different from the other tRNA genes in that its promoter contains two external elements, a PSE and a TATA box functionally equivalent to those of the U6 snRNA gene. Of the two internal promoters governing classical tRNA gene transcription, only subsists the internal B box. In this report, we show that the tRNA((Ser)Sec) contains in addition an activator element (AE) which we have mapped by extensive mutagenesis. Activation is only dependent on a 15 bp fragment residing between -209 and -195 and containing an SPH motif. In vitro, this element forms a complex with a nuclear protein which is different from the TEF-1 transcriptional activator that binds the SV40 Sph motifs. This AE is versatile since it shows capacity of activating a variety of genes in vivo, including U1 and U6 snRNAs and HSV thymidine kinase. Unexpectedly for an snRNA-related gene, the tRNA((Ser)Sec) is deprived of octamer or octamer-like motifs. The X.laevis tRNA((Ser)Sec) gene represents the first example of a Pol III snRNA-type gene whose activation of transcription is completely octamer-independent.
Myslinski
E
E
Institut de Biologie Moléculaire et Cellulaire du CNRS, Strasbourg, France.
Krol
A
A
Carbon
P
P
D000818:Animals; D001483:Base Sequence; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000235:genetics; D004742:Enhancer Elements, Genetic / Q000235:genetics* / Q000502:physiology; D005786:Gene Expression Regulation / Q000235:genetics*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics; D012342:RNA, Small Nuclear / Q000235:genetics; D012345:RNA, Transfer, Amino Acid-Specific / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013539:Simian virus 40 / Q000235:genetics*; D016385:TATA Box / Q000235:genetics; D014982:Xenopus laevis / Q000235:genetics*
D004268:DNA-Binding Proteins; D012342:RNA, Small Nuclear; D012345:RNA, Transfer, Amino Acid-Specific; D011993:Recombinant Fusion Proteins; C036928:tRNA, selenocysteine-