title: N-termini of fungal CSL transcription factors are disordered, enriched in regulatory motifs and inhibit DNA binding in fission yeast.
abstract: BACKGROUND
  CSL (CBF1/RBP-Jκ/Suppressor of Hairless/LAG-1) transcription factors are the effector components of the Notch receptor signalling pathway, which is critical for metazoan development. The metazoan CSL proteins (class M) can also function in a Notch-independent manner. Recently, two novel classes of CSL proteins, designated F1 and F2, have been identified in fungi. The role of the fungal CSL proteins is unclear, because the Notch pathway is not present in fungi. In fission yeast, the Cbf11 and Cbf12 CSL paralogs play antagonistic roles in cell adhesion and the coordination of cell and nuclear division. Unusually long N-terminal extensions are typical for fungal and invertebrate CSL family members. In this study, we investigate the functional significance of these extended N-termini of CSL proteins.
  
  
  RESULTS
  We identify 15 novel CSL family members from 7 fungal species and conduct bioinformatic analyses of a combined dataset containing 34 fungal and 11 metazoan CSL protein sequences. We show that the long, non-conserved N-terminal tails of fungal CSL proteins are likely disordered and enriched in phosphorylation sites and PEST motifs. In a case study of Cbf12 (class F2), we provide experimental evidence that the protein is proteolytically processed and that the N-terminus inhibits the Cbf12-dependent DNA binding activity in an electrophoretic mobility shift assay.
  
  
  CONCLUSIONS
  This study provides insight into the characteristics of the long N-terminal tails of fungal CSL proteins that may be crucial for controlling DNA-binding and CSL function. We propose that the regulation of DNA binding by Cbf12 via its N-terminal region represents an important means by which fission yeast strikes a balance between the class F1 and class F2 paralog activities. This mode of regulation might be shared with other CSL-positive fungi, some of which are relevant to human disease and biotechnology.
authors.affiliation: Department of Genetics, Evolution & Environment and UCL Cancer Institute, University College London, London, United Kingdom. m.prevorovsky@ucl.ac.uk
authors.forename: Martin
authors.initials: M
authors.lastname: Převorovský
authors.forename: Sophie R
authors.initials: SR
authors.lastname: Atkinson
authors.forename: Martina
authors.initials: M
authors.lastname: Ptáčková
authors.forename: Janel R
authors.initials: JR
authors.lastname: McLean
authors.forename: Kathleen
authors.initials: K
authors.lastname: Gould
authors.forename: Petr
authors.initials: P
authors.lastname: Folk
authors.forename: František
authors.initials: F
authors.lastname: Půta
authors.forename: Jürg
authors.initials: J
authors.lastname: Bähler
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D017124:Conserved Sequence / Q000235:genetics; D004247:DNA / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes / Q000378:metabolism; D010748:Phosphopeptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics*; D012568:Schizosaccharomyces / Q000235:genetics* / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: C569834:Cbf11 protein, S pombe; C569835:Cbf12 protein, S pombe; D005656:Fungal Proteins; D015345:Oligonucleotide Probes; D010748:Phosphopeptides; D029702:Schizosaccharomyces pombe Proteins; D014157:Transcription Factors; D004247:DNA