Project description:Methylation of H3 lysine 4 (H3K4me) marks transcribed elements of eukaryotic genome, and their distribution alters dynamically through developmental stages and environmental change. These dynamic regulations are likely achieved by combinatorial work of H3K4me writers, which multi-cellular organisms carry multiple copies of. To better understand the chromatin targeting mechanisms of H3K4 methyltransferase in plants, here we comparatively characterized the seven H3K4 methyltransferases in model plants Arabidopsis. This work clarified, in combination with previous results, ATX1-5 (TRX/TRR-type methyltransferase) localizes on loci with specific sets of chromatin modifications and DNA motifs. Notably, ATX3 localizes to binding motifs of ASR3 and RAP2.11 transcriptional factors and also directly interacts with those TFs. ATXR7(SET1-type) and ATXR3 (non-canonical H3K4 methyltransferase) seemed co-transcriptional. Interestingly, ATXR3, the major H3K4me3 methyltransferase in Arabidopsis, was not associated with COMPASS, which suggests H3K4me3 regulation in plants and animals is divergent. Our work provides a foundation for understanding the regulation of H3K4 methyltransferases in plants.
Project description:Plant stress caused by pathogens or though abiotic means (e.g. drought or temperature) reduces agricultural yields, causing substantial economic losses while reducing food security at the global level. It is critical to recognize how plants perceive stress signals to elicit responses for survival. Endogenous plant peptidases and their peptide products play an important role in the signaling of plant immune processes. Thimet oligopeptidases (TOPs) are zinc-dependent peptide hydrolases with a conserved HEXXH active site motif. These metallopeptidases are critical components in plant response to oxidative stress triggered by pathogens or abiotic factors and are required for a fully functioning immune response to certain pathogens. Further characterization of plant TOPs and their peptide substrates would provide insights into their contribution to defense signaling, stress perception, and plant adaptation pathways. Herein, a quantitative mass spectrometry-based peptidomics approach was implemented to characterize the Arabidopsis thaliana plant peptidome and in the context TOPs (Fig. 1). A comparison between wild type (Col-0) and top1top2 null mutant revealed putative direct and indirect TOPs substrates in vivo.
