The Roles of Transcriptional Co-repressors in Plants
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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
proteins involved in JA biosynthesis and perception have been cloned from various plant species and some of them have been crystallized (e.g. 13-LOX, 13-AOS, AOC, ACYL-CoA-OXIDASE1, OPR3, JAR1 and the SCFCOI1–JAZ-co-receptor complex) (Kombrink, 2012; Wasternack and Hause, 2013).
As a ubiquitously occurring plant growth regulator, JA has been reported to contribute significantly in plant stress defense by playing role as a signal of developmentally or
transferrable process that involves a catalytic process, which differs from the previously known antisense silencing that ssRNAs directly bind to the complement mRNA targets to repress translation by blocking ribosome access. Subsequently, Tuschl and co-workers demonstrated that RNAi mechanism exists in mammalian cell lines for the introduction of synthetic
Name: _Leroy Johnson __________________________________ Date: ______________Comprehensive Study Guide. Test will only be Multiple choice
1. The feature that most clearly separates eukaryotes from prokaryotes is the presence of _______ in eukaryotic cells.
A) ribosomes
B) oxidative phosphorylation
C) DNA molecules
-D) a nucleus
2. Cytoplasmic organelles are
- A) absent in prokaryotic cells; present in eukaryotic cells.
B) present in both prokaryotic and eukaryotic cells