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RNA polymerase III under control: repression and de-repression
Magdalena Boguta1, Damian Graczyk
1Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland. magda@ibb.waw.pl
Trends in Biochemical Sciences
|August 6, 2011
Summary
Yeast RNA polymerase III (Pol III) transcription is regulated by Maf1, a global repressor. Casein kinase II (CK2) phosphorylates Maf1 on tDNA chromatin, controlling Pol III recycling and gene expression.
Area of Science:
- Molecular Biology
- Gene Regulation
- Biochemistry
Background:
- RNA polymerase III (Pol III) transcribes tRNA genes, essential for protein synthesis.
- Maf1 is a conserved global negative regulator of Pol III transcription.
- Pol III activity is modulated by environmental cues, impacting cellular function.
Purpose of the Study:
- To elucidate the molecular mechanism of Pol III repression by Maf1.
- To investigate the role of Maf1 phosphorylation in Pol III regulation.
- To identify kinases that regulate Maf1 activity.
Main Methods:
- Structural and biochemical analyses of Pol III and Maf1.
- Phosphorylation assays using purified Maf1 and kinases.
- In vivo studies assessing Pol III transcription upon environmental shifts.
Main Results:
- Maf1 phosphorylation is crucial for efficient Pol III transcription upon glucose refeeding.
- Casein kinase II (CK2) is identified as a novel kinase that phosphorylates Maf1.
- Maf1 phosphorylation by CK2 occurs directly on tDNA chromatin.
Conclusions:
- CK2-mediated phosphorylation of Maf1 on tDNA chromatin represents a novel regulatory mechanism for Pol III.
- This mechanism controls the recycling of Pol III, thereby regulating tRNA gene transcription.
- Understanding this pathway provides insights into cellular adaptation to environmental changes.
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