The vacuolar processing enzyme OsVPE1 is required for efficient glutelin processing in rice.
Yihua Wang1, Susong Zhu, Shijia Liu
1Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, China.
The Plant Journal : for Cell and Molecular Biology
|January 22, 2009
Summary
A novel rice glutelin mutant, W379, reveals that OsVPE1 is crucial for glutelin maturation. This cysteine protease
Area of Science:
- Plant molecular biology
- Protein biochemistry
- Genetics
Background:
- Rice storage proteins, prolamines and glutelins, are vital for grain nutrition.
- Glutelins are synthesized as precursors and processed in vacuoles into subunits.
Purpose of the Study:
- To identify the gene responsible for a novel rice glutelin mutant (W379) with accumulated glutelin precursors.
- To elucidate the function of the identified gene in glutelin maturation.
Main Methods:
- Map-based cloning was used to identify the causative gene, OsVPE1.
- Genetic analysis and nucleotide sequencing were performed to characterize the mutation.
- In vivo and in vitro assays were used to assess protein processing and enzymatic activity.
Main Results:
- A single recessive nuclear gene, OsVPE1, controls the W379 phenotype.
- A missense mutation (Cys269 to Gly) in OsVPE1 eliminates its enzymatic activity and impairs glutelin maturation.
- Mutant OsVPE1 is incorrectly cleaved, leading to a smaller mature protein.
Conclusions:
- OsVPE1 is a cysteine protease essential for rice glutelin maturation.
- Cys269 in OsVPE1 is critical for its Asn-specific cleavage activity.
- Understanding OsVPE1 function can inform strategies for improving rice protein quality.
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