The Roles of Transcriptional Co-repressors in Plants

The Roles of Transcriptional Co-repressors in Plants Introduction Transcriptional repression is an important process in many biological pathways. These include development, maintaining homeostasis and regulating physiological processes. In order to control the multitude of pathways, there are a number of repressive mechanisms that are elicited by a diverse set of proteins. These proteins can be broadly classified based on their functional properties. For example, some repressors function at cis-regulatory elements to directly interfere with transcriptional machinery (Fig. 1b). Other repressors alter the chromatin structure surrounding a gene (Fig. 1a), which in turn represses transcription in a less direct fashion. Transcriptional repressors can also be defined by whether they bind DNA directly or bind DNA bound transcription factors to modulate their function (Fig. 1c, d). Proteins that use the later mechanism are termed co-repressors [1]. The Groucho/Tup1 (Gro/Tup1) class is a conserved family of co-repressors found in a range of eukaryotic organisms, established by the metazoan protein Groucho. Figure 1 - Diversity and classifications of repressors. (a) Repressors can prevent transcription by modifying chromatin. Proteins recruited by the repressor such as histone deacetylase (HDAC), de-novo methyltransferase (Dnmt) and Swi/Snf modify chromatin surrounding a gene to reduce transcription. (b) Repressors prevent gene expression by interfering with transcriptional