Pea legumin overexpressed in wheat endosperm assembles into an ordered paracrystalline matrix

Area of Science:

• Plant Biotechnology
• Molecular Biology
• Protein Crystallography

Background:

• Legumin, a key pea seed storage protein, comprises heterogeneous subunits complicating structural analysis.
• Posttranslational cleavage and mixed hexamer formation in native legumin hinder in vitro crystallization.

Purpose of the Study:

• To produce a single, homogenous type of pea legumin A in a heterologous system.
• To overcome challenges in structural studies of legumin by enabling in vivo crystallization.

Main Methods:

• Expression of pea legumin A in transgenic wheat (Triticum aestivum) endosperm.
• Analysis of posttranslational processing and 11S hexamer assembly in wheat.
• Characterization of legumin deposition and crystal formation within wheat endosperm inclusions.

Main Results:

• Transgenic wheat successfully produced and posttranslationally processed pea legumin A.
• Homogenous legumin assembled into 11S hexamers and deposited in specific inclusion body regions.
• High-level production of homogenous legumin led to spontaneous in vivo crystal formation.

Conclusions:

• Transgenic wheat endosperm is a viable system for producing homogenous 11S legume globulins.
• This approach facilitates structural analysis and characterization of legumin proteins.
• In vivo crystallization in heterologous systems opens new avenues for protein structure determination.