植物转录抑制子的结构特征及其作用机理

Structural Features and Action Mechanisms of Plant Transcriptional Repressors

转录因子依转录调控能力可分为激活子和抑制子。植物转录抑制蛋白的分类依据很多,从作用方式上可分为主动抑制子和被动抑制子两大类;根据与DNA结合的方式则可分为锌指类、MYB类、AP2/EREBP类、bHLH类和bZIP类等。植物主动抑制子通过其含有的抑制域对转录直接起抑制作用。抑制域又可分很多类,但多数为含有类似EAR基序的保守性基序,其上具有几个保守性亮氨酸残基。植物转录抑制子主要通过对激活子或基本转录复合物产生作用及改变染色体结构3种方式来抑制目标基因的转录。有关植物转录抑制子的研究虽很欠缺,但以拟南芥SUPERMAN等抑制子的EAR基序为代表的研究表明,抑制域是阐明植物转录抑制子功能和下游基因表达调控机理的核心对象,而融合抑制子沉默技术(CRES-T)也为人为调控基因沉默带来了新的技术手段。

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.