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Optimal tRNA((Ser)Sec) gene activity requires an upstream SPH motif
E Myslinski1, A Krol, P Carbon
1Institut de Biologie Moléculaire et Cellulaire du CNRS, Strasbourg, France.
Nucleic Acids Research
|January 25, 1992
Summary
The Xenopus laevis tRNA((Ser)Sec) gene has a unique promoter with an activator element (AE) containing an SPH motif. This AE activates transcription independently of octamer motifs, unlike other snRNA genes.
Area of Science:
- Molecular Biology
- Gene Regulation
- Xenopus laevis Research
Background:
- The Xenopus laevis tRNA((Ser)Sec) gene exhibits unique promoter characteristics compared to other tRNA genes.
- It shares similarities with U6 snRNA genes, possessing external promoter elements like PSE and TATA box, and an internal B box.
Purpose of the Study:
- To investigate the regulatory elements governing the transcription of the X. laevis tRNA((Ser)Sec) gene.
- To identify and characterize novel promoter elements, particularly an activator element (AE).
Main Methods:
- Extensive mutagenesis of the tRNA((Ser)Sec) promoter region.
- In vitro complex formation assays with nuclear proteins.
- In vivo reporter gene assays to assess activation capacity.
Main Results:
- A novel activator element (AE), a 15 bp fragment with an SPH motif, was identified between -209 and -195.
- The AE forms a complex with a nuclear protein distinct from TEF-1.
- The AE demonstrates versatility, activating U1, U6 snRNAs, and HSV thymidine kinase genes in vivo.
- The tRNA((Ser)Sec) gene lacks octamer motifs, which are typically found in snRNA genes.
Conclusions:
- The X. laevis tRNA((Ser)Sec) gene utilizes an octamer-independent transcriptional activation mechanism.
- This finding establishes the tRNA((Ser)Sec) gene as the first Pol III snRNA-type gene with completely octamer-independent transcription activation.