Hydrogen sulfide improves salt tolerance through persulfidation of PMA1 in Arabidopsis

Key message A new interaction was found between PMA1 and GRF4. H 2 S promotes the interaction through persulfidated Cys446 of PMA1. H 2 S activates PMA1 to maintain K + /Na + homeostasis through persulfidation under salt stress. Abstract 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 (H 2 S), a small signaling gas molecule, plays the important roles in facilitating adaptation of plants to salt stress. However, how H 2 S regulates PMA activity remains largely unclear. Here, we show a possible original mechanism for H 2 S 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. H 2 S-mediated persulfidation promoted the binding of PMA1 to GRF4. Further studies showed that H 2 S enhanced instantaneous H + efflux and maintained K + /Na + homeostasis under salt stress. In light of these findings, we suggest that H 2 S promotes the binding of PMA1 to GRF4 through persulfidation, and then activating PMA, thus improving the salt tolerance of Arabidopsis .