Hydrogen Sulfide Disturbs Actin Polymerization via -Sulfhydration Resulting in Stunted Root Hair Growth.

Hydrogen sulfide (HS) is an important signaling molecule in plants. Our previous report suggested that HS signaling affects the actin cytoskeleton and root hair growth. However, the underlying mechanisms of its effects are not understood. -Sulfhydration of proteins is regulated directly by HS, which converts the thiol groups of cysteine (Cys) residues to persulfides and alters protein function. In this work, we studied the effects of -sulfhydration on actin dynamics in Arabidopsis (). We generated transgenic plants overexpressing the HS biosynthesis-related genes () and in the () mutant and Columbia-0 backgrounds. The HS content increased significantly in overexpressing / plants. The density of filamentous actin (F-actin) bundles and the F-actin/globular actin ratio decreased in overexpressing / plants. -Sulfhydration also was enhanced in overexpressing / plants. An analysis of actin dynamics suggested that -sulfhydration inhibited actin polymerization. We also found that ACTIN2 (ACT2) was -sulfhydrated at Cys-287. Cys-287 is adjacent to the D-loop, which acts as a central region for hydrophobic and electrostatic interactions and stabilizes F-actin filaments. Overaccumulation of HS caused the depolymerization of F-actin bundles and inhibited root hair growth. Introduction of carrying a Cys-287-to-Ser mutation into an mutant partially suppressed HS-dependent inhibition of root hair growth. We conclude that HS regulates actin dynamics and affects root hair growth.