Temporal dynamics of protein phosphorylation and S-nitrosylation direct maize seed germination programs

Area of Science:

• Plant Biology
• Proteomics
• Biochemistry

Background:

• Seed germination is crucial for crop yield, yet the role of post-translational modifications (PTMs) is understudied.
• Hormonal and transcriptional regulation of germination are known, but PTMs like phosphorylation and S-nitrosylation remain largely unexplored.

Purpose of the Study:

• To develop a novel proteomics workflow for simultaneous, site-specific profiling of phosphorylation and S-nitrosylation during maize seed germination.
• To comprehensively map the maize seed germination S-nitrosoproteome and phosphoproteome.

Main Methods:

• Developed a phosphate-affinity tag-switch (PAT-switch) proteomics workflow.
• Performed site-specific profiling of phosphorylation and S-nitrosylation.
• Utilized kinase activity assays, western blotting, and molecular dynamics simulations.

Main Results:

• Identified over 5921 S-nitrosylation sites and 15,947 phosphorylation sites.
• Phosphorylation peaks early, activating metabolism; S-nitrosylation is prominent later, fine-tuning redox balance.
• Discovered reciprocal regulation of SnRK1α kinase activity by adjacent S-nitrosylation and phosphorylation.

Conclusions:

• PTM dynamics and interactions are critical for maize seed germination and seedling establishment.
• Findings provide novel insights into PTM networks for potential crop improvement strategies.
• The study highlights the importance of inter-PTM crosstalk in developmental transitions.