Plant-TFClass: a structural classification for plant transcription factors

Transcription factors (TFs) bind DNA at specific sequences to regulate gene expression. This universal process is achieved via their DNA-binding domain (DBD). In mammals, the vast diversity of DBD structural conformations and the way in which they contact DNA has been used to organize TFs in the TFClass hierarchical classification. However, the numerous DBD types present in plants but absent from mammalian genomes were missing from this classification. We reviewed DBD 3D structures and models available for plant TFs to classify most of the 56 recognized plant TF types within the TFClass framework. This extended classification adds eight new classes and 37 new families corresponding to DBD structures absent in mammals. Plant-TFClass provides a unique resource for TF comparison across families and organisms.