Moonlighting Arabidopsis molybdate transporter 2 family and GSH-complex formation facilitate molybdenum homeostasis
Jan-Niklas Weber, Rieke Minner-Meinen, Maria Behnecke, Rebekka Biedendieck, Veit G. Hänsch, Thomas W. Hercher, Christian Hertweck, Lena van den Hout, Lars Knüppel, Simon Sivov, Jutta Schulze, Ralf R. Mendel, Robert Hänsch, David Kaufholdt
Abstract
Molybdenum (Mo) as essential micronutrient for plants, acts as active component of molybdenum cofactor (Moco). Core metabolic processes like nitrate assimilation or abscisic-acid biosynthesis rely on Moco-dependent enzymes. Although a family of molybdate transport proteins (MOT1) is known to date in Arabidopsis, molybdate homeostasis remained unclear. Here we report a second family of molybdate transporters (MOT2) playing key roles in molybdate distribution and usage. KO phenotype-analyses, cellular and organ-specific localization, and connection to Moco-biosynthesis enzymes via protein-protein interaction suggest involvement in cellular import of molybdate in leaves and reproductive organs. Furthermore, we detected a glutathione-molybdate complex, which reveals how vacuolar storage is maintained. A putative Golgi S-adenosyl-methionine transport function was reported recently for the MOT2-family. Here, we propose a moonlighting function, since clear evidence of molybdate transport was found in a yeast-system. Our characterization of the MOT2-family and the detection of a glutathione-molybdate complex unveil the plant-wide way of molybdate.