Structural Features and Action Mechanisms of Plant Transcriptional Repressors

Transcription factor can act as an activator or a repressor. Although multiple standards can be used to classify plant repressors, repressors can be primarily divided into active and passive repressors according to their action mechanism. Like activators, repressors also possess various DNA binding domains such as zinc-finger, MYB, AP2/EREBP, bHLH, and bZIP domains. Plant active repressors directly repress transcription via their repression domains. Different types of repression domains exist, but most of them contain EAR or EAR-like motifs that harbor several conservative leucine residues. Plant repressors repress transcription of target genes by interacting with activators, acting on the basal transcription-factor complex or remodeling chromosome structures. Study of plant repressors is insufficient, but characterization of EAR motifs of repressors such as Arabidopsis SUPERMAN suggests that repression domains are core targets for elucidating the functions of plant repressors and the expression regulation mechanisms of their downstream genes. Chimeric repressor silencing technology (CRES-T) also provides a new method for artificial silencing of plant regulatory genes.