# Nitric Oxide-mediated S-nitrosylation of the Energy Sensor KIN10 Regulates RNA Splicing and Gene Expression in Arabidopsis

## TL;DR

This study shows how nitric oxide regulates gene expression in plants by modifying a protein called KIN10, which affects RNA splicing.

## Contribution

The study reveals a molecular mechanism linking nitric oxide signaling to RNA splicing through S-nitrosylation of KIN10.

## Key findings

- NO-mediated S-nitrosylation at Cys-177 stabilizes KIN10 and enhances its activity.
- S-nitrosylation of KIN10 modulates phosphorylation of splicing factors in the spliceosome.
- A KIN10 mutant lacking nitrosylation is insensitive to NO and functionally impaired.

## Abstract

Nitric oxide (NO) is a crucial signaling molecule involved in various developmental processes and stress responses through post-translational protein modification and modulation of gene expression. Despite significant advances in understanding the mechanism of NO-mediated protein modifications, how NO regulates gene expression remains largely unclear. Here, we show that the energy sensor KIN10, a catalytic α-subunit of sucrose non-fermenting 1-related kinase 1, plays a vital role in NO-mediated regulation of gene expression in Arabidopsis. NO-mediated S-nitrosylation at Cys-177 of KIN10 inhibits its degradation, leading to protein stabilization. A non-nitrosylatable mutation of Cys-177 to serine results in NO insensitivity and functional deficiencies. Quantitative phosphoproteomic analysis reveals that S-nitrosylation at Cys-177 of KIN10 modulates the phosphorylation of splicing factors within the spliceosome. We propose that NO regulates RNA splicing through the enhancement of KIN10 activity via S-nitrosylation, thereby establishing a molecular link between NO signaling and gene expression.

•KIN10 acts as a positive regulator of nitric oxide signaling.•S-nitrosylation at Cys-177 stabilizes KIN10 protein and enhances its activity.•NO-mediated S-nitrosylation of KIN10 modulates the phosphorylation status of splicing factors within the spliceosome complex.•KIN10 bridges NO signaling and gene expression regulation.

KIN10 acts as a positive regulator of nitric oxide signaling.

S-nitrosylation at Cys-177 stabilizes KIN10 protein and enhances its activity.

NO-mediated S-nitrosylation of KIN10 modulates the phosphorylation status of splicing factors within the spliceosome complex.

KIN10 bridges NO signaling and gene expression regulation.

Nitric oxide (NO) is a key signaling molecule, but how it regulates gene expression is not well understood. Here we show that NO‑dependent S‑nitrosylation of the energy sensor KIN10 stabilizes the protein and alters the phosphorylation of splicing factors in Arabidopsis. kin10 mutant is insensitive to NO and functionally impaired. These findings reveal a molecular link between NO signaling, KIN10 activity, and RNA splicing–mediated regulation of gene expression.