Intrinsically disordered regions of the Msn2 transcription factor encode multiple functions using interwoven sequence...

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Intrinsically disordered regions (IDRs) are prevalent in eukaryotic proteins, yet their sequence-function relationships are not fully understood.
• Transcription factors (TFs) utilize IDRs to regulate gene expression by directing promoter selection and recruiting coactivators.
• The budding yeast TF Msn2 serves as a model to investigate how IDRs encode these dual functions.

Purpose of the Study:

• To elucidate how intrinsically disordered regions (IDRs) of transcription factors (TFs) encode promoter binding specificity and coactivator recruitment.
• To investigate the relationship between sequence variations in the Msn2 IDR and its functions in genomic binding, coactivator recruitment, and gene induction.

Main Methods:

• Generation and analysis of a large set of designed Msn2 IDR mutants.
• Comparison of genomic binding specificity, coactivator recruitment assays, and gene induction levels across mutants.
• Bioinformatic analysis to identify sequence-based codes governing different functions.

Main Results:

• Both DNA binding specificity and transcription activity are influenced by multiple regions within the Msn2 IDR (>600 amino acids).
• Mutations disrupting transcription activity often had no effect on Msn2 binding specificity.
• Differential sensitivity is attributed to a composition-based code for binding specificity versus a stringent motif-based code for coactivator recruitment and transcription.

Conclusions:

• The Msn2 TF employs interwoven sequence grammars within its IDR to encode distinct functions.
• A relaxed, composition-based code governs binding specificity, while a stringent, motif-based code controls transcription.
• This suggests a potentially generalizable IDR design paradigm for encoding multiple protein functions.