Their chromosomal localization, expression, and motif patterns have been studied. In conjunction, the genes coding for transcriptional repressors with a DLN motif in rice have been identified. Based on the property of transferability of repression motifs, we have designed a yeast-based assay, to easily assess the repressive ability of a TF or motif. The roles of many genes involved in development and stress have been elucidated by using CRES-T. It functions over a short range and can cause successful repression of an activator, despite the binding site being present either upstream or downstream to the binding site of the activator. The LxLxL motif in Aux/IAA (Auxin/Indole-3-acetic acid) proteins is transferable and dominant over activation domains. This technique popularly referred to as chimeric repressor silencing technology (CRES-T) can also be exploited for co-activators, which do not have DNA binding capacity. Thus, multifaceted repressors with an EAR motif, many of which have DLNxxP as consensus sequence, eventually cause enhancement or suppression of the downstream response.Ī modified EAR motif, called SRDX (modified SUPRD with the sequence LDLDLELRLGFA SUPRD is a 30 residue C-terminal region of SUPERMAN (SUP) from Arabidopsis, which acts as a repression domain (RD)) and a 32 residue LxLxL-type EAR motif (LDLNLELRISPP) have been successfully used as a dominant repressor in fusion with TFs, to identify the functionality of redundant TFs. Many EAR repressors also function in hormone signaling pathways, negatively regulating jasmonic acid (JA) signaling and ethylene biosynthesis while positively regulating auxin response and brassinosteroid induced repression. Infection by Indian cassava mosaic virus is spread by activation of an EAR motif containing repressor, which suppresses histone methyltransferase. Some repressors activate plant immunity against pathogens by inducing programmed cell death. Additionally, they cause contained expression of downstream genes, preventing self-damage to the plant and imparting a/biotic stress tolerance. They prevent expression of stress associated genes under normal conditions, and control growth during stress, and hence save plant energy. They delimit organ boundaries for proper growth control floral meristem development ovule development and male germ cell division. They regulate plant height spikelet architecture flowering time root hair development shoot branching and secondary metabolite biosynthesis. The EAR repressome is involved in a wide range of functions in plants, from development to stress responses. Comparatively, LxLxL motif occurs at a higher frequency in different plant species. The ERF–EAR motif contributes about 86% of the total plant repressome in Arabidopsis. TLLLFR, KLFGV, ethylene-responsive element binding factor-associated amphiphilic repression (EAR), and NAC-associated repression domain (NARD) are common plant repression motifs. Active repressors have an intrinsic repression motif which interacts with the general transcription factors (TFs) or with other chromatin components, eventually inhibiting the binding of transcriptional activators. Transcriptional repressors act either in an active or passive manner. Regulation of gene expression is an interesting phenomenon with the participation of multiple players, some of which act as repressors of downstream genes and regulate their spatio-temporal expression pattern. The study reports a straightforward assay to analyze repressor activity, along with the identification of a strong DLN repressor from rice. Comparatively, rice has more DLN repressor encoding genes than Arabidopsis, and DLNSPP motif from rice is 40% stronger than the known Arabidopsis SRDX motif. The DLN hexapeptide motif is essential for repression, and at least two “DLN” residues cause maximal repression. We have designed a simple yeast-based experiment wherein a DLN motif can successfully cause strong repression of downstream reporter genes, when fused to a transcriptional activator of rice or yeast. Most of the DLN repressome proteins have a single DLN motif, with higher relative percentage in the C-terminal region. Apart from DLNxxP motif conservation, DLNxP and DLNxxxP motifs with variable numbers/positions of proline and those without any proline conservation have been identified. In rice ( Oryza sativa), we have identified a total of 266 DLN repressor proteins, with the former motif and its modifications thereof comprising 227 transcription factors and 39 transcriptional regulators. They contain either DLNxxP or LxLxL as the identifying hexapeptide motif. In plants, a well-established class of repressors are proteins with an ERF-associated amphiphilic repression/EAR domain. Transcriptional regulation includes both activation and repression of downstream genes.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |