Histone H2A.Z Regulates the Expression of Several【荐】.pdf

Histone H2A.Z Regulates the Expression of Several Classes of Phosphate Starvation Response Genes But Not as a Transcriptional Activator1[OA] 2 3 Aaron P. Smith , Ajay Jain, Roger B. Deal , Vinay K. Nagarajan, Michael D. Poling, Kashchandra G. Raghothama, and Richard B. Meagher* Department of Genetics, University of Georgia, Fred C. Davison Life Sciences Complex, Athens, Georgia, 30602 (A.P.S., A.J., R.B.D., R.B.M.); and Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907 (V.K.N., M.D.P., K.G.R.) Phosphate (Pi) availability is a major constraint to plant growth. Consequently, plants have evolved complex adaptations to tolerate low Pi conditions. Numerous genes implicated in these adaptations have been identified, but their chromatin-level regulation has not been investigated. The nuclear actin-related protein ARP6 is conserved among all eukaryotes and is an essential component of the SWR1 chromatin remodeling complex, which regulates transcription via deposition of the H2A.Z histone variant into chromatin. Here, we demonstrate that ARP6 is required for proper H2A.Z deposition at a number of Pi starvation response (PSR) genes in Arabidopsis (Arabidopsis thaliana). The loss of H2A.Z at these target loci results in their derepression in arp6 mutants and correlates with the presence of multiple Pi-starvation-related phenotypes, including shortened primary roots and increases in the number and length of root hairs, as well as increased starch accumulation and phosphatase activity in shoots. Our data suggest a model for chromatin-level control of Pi starvation responses in which ARP6- dependent H2A.Z deposition modulates the transcription of a suite of PSR genes. All living things require phosphorus (P) for sur- For plants, P availabilit