Hydrogen sulfide improves salt tolerance through persulfidation of PMA1 in Arabidopsis

Key messageA new interaction was found between PMA1 and GRF4. H2S promotes the interaction through persulfidated Cys446 of PMA1. H2S activates PMA1 to maintain K+/Na+ homeostasis through persulfidation under salt stress.Plasma membrane H+-ATPase (PMA) is a transmembrane transporter responsible for pumping protons, and its contribution to salt resistance is indispensable in plants. Hydrogen sulfide (H2S), a small signaling gas molecule, plays the important roles in facilitating adaptation of plants to salt stress. However, how H2S regulates PMA activity remains largely unclear. Here, we show a possible original mechanism for H2S to regulate PMA activity. PMA1, a predominant member in the PMA family of Arabidopsis, has a non-conservative persulfidated cysteine (Cys) residue (Cys446), which is exposed on the surface of PMA1 and located in cation transporter/ATPase domain. A new interaction of PMA1 and GENERAL REGULATORY FACTOR 4 (GRF4, belongs to the 14-3-3 protein family) was found by chemical crosslinking coupled with mass spectrometry (CXMS) in vivo. H2S-mediated persulfidation promoted the binding of PMA1 to GRF4. Further studies showed that H2S enhanced instantaneous H+ efflux and maintained K+/Na+ homeostasis under salt stress. In light of these findings, we suggest that H2S promotes the binding of PMA1 to GRF4 through persulfidation, and then activating PMA, thus improving the salt tolerance of Arabidopsis.