Submitted to: Proceedings of the National Academy of Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/2006
Publication Date: 4/11/2006
Citation: Alvarez-Venegas, R., Sadder, M., Hlavacka, A., Baluska, F., Xia, Y., Lu, G., Firsov, A., Sarath, G., Moriyama, H., Dubrovsky, J., Avramova, Z. 2006. The arabidopsis homolog of trithorax, atx1, binds phosphatidyi inosito-5-phosphate, and the two regulate a common set of target genes. 103:6049-6054. Interpretive Summary: Plant development is a complex process involving the interplay of gene regulation in response to internal or external signaling. Most commonly signaling pathways in plants consists of several proteins that must interact in a specific manner to elicit resultant changes in gene function. Thus, signaling pathways are crucial to orderly plant development and of considerable interest to researchers. Finding evidence for new signaling pathways is rare and therefore really exciting. In this study, Dr. Avramova and her collaborators show that a plant protein called ATX1 from the model organism, Arabidopsis thaliana, probably participates in signaling involving a cellular molecule termed phospatidyl inositol 5 phosphate (PI-5P). Our research also provides structural models that highlight the PI-5P binding domain on ATX-1 and its probable involvement as a receptor for lipid secondary messenger molecules. These data also show that recombinant ATX-1 will bind specifically to PI-5P and can translocate to the nucleus in stimulated cells. Since ATX-1 protein has the domain that can catalyze histone lysine methyaltion, its migration to the nucleus in response to PI-5P signaling could be responsible for the known actions of the ATX-1 gene in plant development.
Technical Abstract: The Arabidopsis homolog of trithorax, ATX1, is a pleiotropic developmental factor upregulating a few flower homeotic genes, most likely by modifying the chromatin structure via the histone methylase activity of its SET domain. Here, we show that in Arabidopsis root cells, ATX1 may have both nuclear and cytoplasmic localization and that ATX1 can specifically bind Phosphatidyl Inositol-5 Phosphate (PI(5)P). The PHDATX1 finger is involved in the binding and acts as a receptor for lipid secondary messenger molecules. The results implicate ATX1 in a different function as a participant in a novel Phospahtidyl-Inositil (PI)-signaling pathway.