Nuclear Localised MORE SULPHUR ACCUMULATION1 Epigenetically Regulates Sulphur Homeostasis in Arabidopsis thaliana.

• Main Authors: Xin-Yuan Huang, Dai-Yin Chao, Anna Koprivova, John Danku, Markus Wirtz, Steffen Müller, Francisco J Sandoval, Hermann Bauwe, Sanja Roje, Brian Dilkes, Rüdiger Hell, Stanislav Kopriva, David E Salt
• Format: Article
• Language: English
• Published: Public Library of Science (PLoS) 2016-09-01
• Series: PLoS Genetics
• Online Access: http://europepmc.org/articles/PMC5021336?pdf=render

Sulphur (S) is an essential element for all living organisms. The uptake, assimilation and metabolism of S in plants are well studied. However, the regulation of S homeostasis remains largely unknown. Here, we report on the identification and characterisation of the more sulphur accumulation1 (msa1-1) mutant. The MSA1 protein is localized to the nucleus and is required for both S-adenosylmethionine (SAM) production and DNA methylation. Loss of function of the nuclear localised MSA1 leads to a reduction in SAM in roots and a strong S-deficiency response even at ample S supply, causing an over-accumulation of sulphate, sulphite, cysteine and glutathione. Supplementation with SAM suppresses this high S phenotype. Furthermore, mutation of MSA1 affects genome-wide DNA methylation, including the methylation of S-deficiency responsive genes. Elevated S accumulation in msa1-1 requires the increased expression of the sulphate transporter genes SULTR1;1 and SULTR1;2 which are also differentially methylated in msa1-1. Our results suggest a novel function for MSA1 in the nucleus in regulating SAM biosynthesis and maintaining S homeostasis epigenetically via DNA methylation.