Abstract
Transcriptional regulation includes both activation and repression of downstream genes. In plants, a well-established class of repressors are proteins with an ERF-associated amphiphilic repression/EAR domain. They contain either DLNxxP or LxLxL as the identifying hexapeptide motif. 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. Apart from DLNxxP motif conservation, DLNxP and DLNxxxP motifs with variable numbers/positions of proline and those without any proline conservation have been identified. Most of the DLN repressome proteins have a single DLN motif, with higher relative percentage in the C-terminal region. 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. The DLN hexapeptide motif is essential for repression, and at least two “DLN” residues cause maximal repression. 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 study reports a straightforward assay to analyze repressor activity, along with the identification of a strong DLN repressor from rice.
Highlights
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 maximum numbers of the DLN repressors of rice belonged to C2H2 zinc finger family, with MYB, NAC, AP2 and PHD as other prominent families (Tables S1–S3)
We have previously reported the presence of this motif in ZOS transcription factors (TFs) [30] and have shown NAC TFs to act as repressors [31,32]
Summary
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 EAR repressome is involved in a wide range of functions in plants, from development to stress responses They regulate plant height [4]; spikelet architecture [5]; flowering time [6]; root hair development [7]; shoot branching [8]; and secondary metabolite biosynthesis [9]. They delimit organ boundaries for proper growth [10]; control floral meristem development [11]; ovule development [12]; and male germ cell division [13]. Multifaceted repressors with an EAR motif, many of which have DLNxxP as consensus sequence, eventually cause enhancement or suppression of the downstream response
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