Protein persulfidation: a ubiquitous modification regulating a broad spectrum of biological processes.

Hydrogen sulfide signaling occurs mainly through protein persulfidation, an important post-translational modification and a highly dynamic process in plants. Beyond enzyme activity, persulfidation affects protein localization, structure, and interactions. This review provides an overview of the mechanisms governing this modification and the pivotal role of the thioredoxin system mediating depersulfidation, which is essential for maintaining redox homeostasis. Proteomic studies in Arabidopsis thaliana and crop species reveal that protein persulfidation is a widespread post-translational modification in plants, with over 11 700 polypeptides identified as susceptible. Functional analysis shows a high proportion of these proteins are involved in primary metabolic pathways and secondary metabolism. Gene Ontology analysis highlights additional processes regulated by persulfidation, underscoring its broad regulatory role in plant biology. These processes are mainly related to proteolysis, defense response, embryo development, protein transport, and response to cold. In addition, other processes regulated by hydrogen sulfide, which have been widely studied, also stand out, such as response to abscisic acid, response to oxidative stress, and response to water deprivation. A comprehensive description of the persulfidated proteins implicated in the processes highlighted by the Gene Ontology analysis is provided. This integrated role of H2S with other molecules offers a panoramic overview of its importance in plant biology which also helps to raise new questions and working directions for the future research.