Nitrosoproteomic Analysis Deciphers the S-Nitrosylome in Carbon Metabolism of Tea Leaves

Cysteine S-nitrosylation is a reversible protein post-translational modification and critically regulates the activity, localization and stability of proteins. Tea (Camellia sinensis (L.)) is one of the most thoroughly studied evergreen crop due to its broad non-alcoholic beverage and huge economic impact in the world. However, to date, little is known about the S-nitrosylome in this plant. Here, we performed a global analysis of cysteine S-nitrosylation in tea leaves. In total, 228 cysteine S-nitrosylation sites were identified in 191 proteins, representing the first extensive data on the S-nitrosylome in tea plants. These S-nitrosylated proteins were located in multiple subcellular compartments, especially in the chloroplast and cytoplasm. The analysis of functional enrichment and PPI network revealed that the S-nitrosylated proteins were mainly involved in carbon metabolism, especially in Calvin cycle and TCA cycle. These results suggested that S-nitrosylated proteins in tea leaves might play critical regulatory roles in the carbon metabolism. Overall, this study not only globally analyzed the functional annotation of cysteine S-nitrosylation in tea leaves, but also preliminarily provided the valuable information for further investigating the functions of cysteine S-nitrosylation in tea plants.