H2S Persulfidated and Increased Kinase Activity of MPK4 to Response Cold Stress in Arabidopsis

Abstract

Hydrogen sulfide (H₂S) is a gasotransmitter along with nitric oxide and carbon oxide, which is involved in plant growth and development as well as biotic and abiotic stress resistance. In a previous study, we reported that mitogen-activated protein kinases, especially MPK4, are important downstream components of H₂S involved in alleviating cold stress; however the underlying mechanism is unclear. In this study, we determined that the ability of H₂S to alleviate cold stress is impaired in <i>mpk4</i> mutants, but not in the upstream <i>mek2</i> and <i>crlk1</i> mutants. MPK4 was basically persulfidated, and NaHS (H₂S donor) further increased the persulfidation level of MPK4. MEK2 was not persulfidated by H₂S. NaHS treatments increased the MPK4 activity level nearly tenfold. The persulfidation signal of MPK4 did not disappear after eight cystein residues in MPK4 were site-mutated, respectively. Above all, our results suggested that H₂S alleviates cold stress directly by persulfidating MPK4 and increasing the MPK4 kinase activity.