R2R3 MYB Transcription Factors – Functions outside the DNA-Binding Domain

The DBDs of R2R3 MYB TFs have high sequence conservation and their molecular function is understood in a structural context. Conversely, the non-MYB regions are highly divergent and variable in length, and structural understanding is completely lacking. These regions are consistently predicted to contain extensive IDRs; because of their diversity, these are likely to be determinants of functional specialization across the family. Although IDRs have been shown to perform specific tasks in an increasing number of proteins, intrinsic structural disorder in the plant R2R3 MYB TF family has not been systematically studied. Non-MYB regions contain subgroup-specific motifs, post-translational modification sites, binding sites for physical interactions, and activation domains, highlighting their functional importance. Several transcription factor (TF) families, including the MYB family, regulate a wide array of biological processes. TFs contain DNA-binding domains (DBDs) and regulatory regions; although information on protein structure is scarce for plant MYB TFs, various in silico methods suggest that the non-MYB regions contain extensive intrinsically disordered regions (IDRs). Although IDRs do not fold into stable globular structures, they comprise functional regions including interaction motifs, and recent research has shown that IDRs perform crucial biological roles. We map here domain organization, disorder predictions, and functional regions across the entire Arabidopsis thaliana R2R3 MYB TF family, and highlight where an increased research focus will be necessary to shape a new understanding of structure–function relationships in plant TFs. Several transcription factor (TF) families, including the MYB family, regulate a wide array of biological processes. TFs contain DNA-binding domains (DBDs) and regulatory regions; although information on protein structure is scarce for plant MYB TFs, various in silico methods suggest that the non-MYB regions contain extensive intrinsically disordered regions (IDRs). Although IDRs do not fold into stable globular structures, they comprise functional regions including interaction motifs, and recent research has shown that IDRs perform crucial biological roles. We map here domain organization, disorder predictions, and functional regions across the entire Arabidopsis thaliana R2R3 MYB TF family, and highlight where an increased research focus will be necessary to shape a new understanding of structure–function relationships in plant TFs.