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A murine ATFa-associated factor with transcriptional repressing activity
F De Graeve1, A Bahr, B Chatton
1Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, Illkirch, Communauté Urbaine de Strasbourg, France.
Abstract:
The ATFa proteins, which are members of the CREB/ATF family of transcription factors, have previously been shown to interact with the adenovirus E1a oncoprotein and to mediate its transcriptional activity; they heterodimerize with Jun, Fos or related transcription factors, possibly altering their DNA-binding specificity; they also stably bind JNK2, a stress-induced protein kinase. Here we report the identification and characterization of a novel protein isolated in a yeast two-hybrid screen using the N-terminal half of ATFa as a bait. This 1306-residue protein (mAM, for mouse ATFa-associated Modulator) is rather acidic (pHi 4.5) and contains high proportions of Ser/Thr (21%) and Pro (11%) residues. It colocalizes and interacts with ATFa in mammalian cells, contains a bipartite nuclear localization signal and possesses an ATPase activity. Transfection experiments show that mAM is able to downregulate transcriptional activity, in an ATPase-independent manner. Our results indicate that mAM interacts with several components of the basal transcription machinery (TFIIE and TFIIH), including RNAPII itself. Together, these findings suggest that mAM may be involved in the fine-tuning of ATFa-regulated gene expression, by interfering with the assembly or stability of specific preinitiation transcription complexes.
Insights
Researchers discovered a new protein, mouse ATFa-associated Modulator (mAM), that fine-tunes gene expression regulated by ATFa transcription factors. mAM interacts with basal transcription machinery to modulate ATFa activity.
Area of Science:
- Molecular Biology
- Gene Regulation
- Protein Interactions
Background:
- ATFa proteins, part of the CREB/ATF family, interact with adenovirus E1a and Jun/Fos transcription factors.
- ATFa proteins bind JNK2, a stress-induced protein kinase.
Purpose of the Study:
- Identify and characterize novel proteins interacting with ATFa.
- Investigate the role of the novel protein in transcriptional regulation.
Main Methods:
- Yeast two-hybrid screening using ATFa N-terminal domain.
- Protein characterization including sequence analysis, colocalization, and interaction studies in mammalian cells.
- Transfection experiments to assess transcriptional activity and ATPase function.
Main Results:
- Identified and characterized a novel 1306-residue protein, mouse ATFa-associated Modulator (mAM).
- mAM colocalizes and interacts with ATFa, possesses ATPase activity, and contains a nuclear localization signal.
- mAM downregulates transcriptional activity independently of its ATPase function and interacts with basal transcription machinery components (TFIIE, TFIIH, RNAPII).
Conclusions:
- mAM is a novel ATFa-interacting protein involved in regulating gene expression.
- mAM may fine-tune ATFa-regulated gene expression by affecting preinitiation transcription complex assembly or stability.
- The findings suggest a new mechanism for modulating transcription factor activity through protein-protein interactions within the basal transcription machinery.