Protein turnover in the developing Triticum aestivum grain

Area of Science:

• Plant Biology
• Proteomics
• Biochemistry

Background:

• Protein abundance in cereal grains is crucial for yield and quality.
• Understanding protein synthesis and degradation dynamics is essential for optimizing grain development.
• Current methods lack precise quantitation of protein turnover rates during grain development.

Purpose of the Study:

• To measure protein turnover rates for approximately 1400 proteins during wheat grain development.
• To investigate the spatiotemporal patterns of protein turnover.
• To determine the energetic costs associated with protein biogenesis and turnover in wheat grains.

Main Methods:

• Utilized in vivo stable isotope labeling combined with in-depth quantitative proteomics.
• Measured protein turnover rates across various protein functional categories.
• Calculated adenosine triphosphate (ATP) production allocated to proteome maintenance and storage protein synthesis.

Main Results:

• Identified spatiotemporal patterns in protein turnover rates, explaining variations in protein abundance not linked to gene expression.
• Demonstrated that approximately 20% of total grain ATP production supports proteome biogenesis and maintenance.
• Revealed that nearly half of the ATP budget is dedicated to storage protein synthesis, with 25% of newly synthesized storage proteins being turned over.
• Characterized the stability of different protein functional categories within developing wheat grains.

Conclusions:

• Protein turnover significantly influences wheat grain protein accumulation and composition.
• The energetic cost of protein turnover, particularly for storage proteins, is substantial during wheat grain development.
• This proteome-scale approach provides novel insights into the dynamics of grain protein metabolism and identifies key regulatory points.