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Updated: May 12, 2026
Microscopy of Fission Yeast Sexual Lifecycle
Published on: March 9, 2016
Fission yeast CSL proteins function as transcription factors
Martina Oravcová1, Mikoláš Teska, František Půta
1Department of Cell Biology, Faculty of Science, Charles University in Prague, Prague, Czech Republic.
Background:
Transcription factors of the CSL (CBF1/RBP-Jk/Suppressor of Hairless/LAG-1) family are key regulators of metazoan development and function as the effector components of the Notch receptor signalling pathway implicated in various cell fate decisions. CSL proteins recognize specifically the GTG[G/A]AA sequence motif and several mutants compromised in their ability to bind DNA have been reported. In our previous studies we have identified a number of novel putative CSL family members in fungi, organisms lacking the Notch pathway. It is not clear whether these represent genuine CSL family members.
Methodology/Principal Findings:
Using a combination of in vitro and in vivo approaches we characterized the DNA binding properties of Cbf11 and Cbf12, the antagonistic CSL paralogs from the fission yeast, important for the proper coordination of cell cycle events and the regulation of cell adhesion. We have shown that a mutation of a conserved arginine residue abolishes DNA binding in both CSL paralogs, similar to the situation in mouse. We have also demonstrated the ability of Cbf11 and Cbf12 to activate gene expression in an autologous fission yeast reporter system.
Conclusions/Significance:
Our results indicate that the fission yeast CSL proteins are indeed genuine family members capable of functioning as transcription factors, and provide support for the ancient evolutionary origin of this important protein family.
Insights
Fission yeast CSL proteins, Cbf11 and Cbf12, are confirmed transcription factors. This discovery supports an ancient evolutionary origin for this crucial protein family in eukaryotes.
Area of Science:
- Molecular Biology
- Evolutionary Biology
- Yeast Genetics
Background:
- CSL (CBF1/RBP-Jk/Suppressor of Hairless/LAG-1) proteins are vital transcription factors regulating development and Notch signaling.
- CSL proteins bind the specific DNA motif GTG[G/A]AA; DNA-binding mutants are known.
- Novel CSL family members were identified in fungi, but their genuine CSL status was uncertain.
Purpose of the Study:
- To investigate the DNA binding properties and transcriptional activity of fission yeast CSL paralogs, Cbf11 and Cbf12.
- To determine if these fungal CSL proteins are authentic members of the CSL family.
Main Methods:
- In vitro and in vivo biochemical assays were employed.
- DNA binding capabilities of Cbf11 and Cbf12 were characterized.
- Gene expression activation was assessed using a fission yeast reporter system.
Main Results:
- A conserved arginine residue mutation was found to abolish DNA binding in both Cbf11 and Cbf12, mirroring findings in mouse CSL proteins.
- Cbf11 and Cbf12 demonstrated the ability to activate gene expression within a fission yeast reporter system.
- The DNA binding and transcriptional functions confirm Cbf11 and Cbf12 as genuine CSL proteins.
Conclusions:
- Fission yeast CSL proteins (Cbf11 and Cbf12) function as bona fide transcription factors.
- These findings support an ancient evolutionary origin for the CSL protein family, predating the Notch pathway.
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