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Dimerization and protease resistance: new insight into the function of PR-1
Shunwen Lu1, Justin D Faris, Robert Sherwood
1USDA-ARS, Cereal Crops Research Unit, Fargo, ND 58102, USA. Shunwen.Lu@ars.usda.gov
Journal of Plant Physiology
|August 28, 2012
Summary
Plant pathogenesis-related (PR-1) proteins from wheat were characterized, revealing their protease resistance and dimerization properties. Conserved residues suggest a role in programmed cell death pathways.
Area of Science:
- Plant Biology
- Biochemistry
- Molecular Biology
Background:
- Group 1 pathogenesis-related (PR-1) proteins are key indicators of plant defense responses.
- Despite structural data, the precise biochemical functions of PR-1 proteins remain largely unknown.
- Previous studies resolved structures of PR-1 like proteins, but functional characterization is limited.
Purpose of the Study:
- To characterize two basic PR-1 proteins (PR-1-1 and PR-1-5) from hexaploid wheat (Triticum aestivum).
- To investigate the biochemical properties, including dimerization and protease resistance, of these wheat PR-1 proteins.
- To explore potential functional roles of PR-1 proteins in plant programmed cell death.
Main Methods:
- Recombinant expression of wheat PR-1 proteins in Pichia pastoris.
- Mass spectrometry (MALDI-TOF/TOF) for protein identification.
- Protein gel blot, low-temperature SDS-PAGE, and yeast two-hybrid assays for protein analysis.
- Site-specific mutagenesis to probe active site functions and protease resistance.
Main Results:
- Both PR-1-1 and PR-1-5 were successfully expressed and verified.
- PR-1-1 exists as a monomer, while PR-1-5 forms homodimers.
- Both proteins exhibit significant protease resistance, with differential sensitivity to various proteases.
- Mutations in putative active sites affected dimerization and protease resistance.
- Conserved residues (Glu-72, Glu-102) link PR-1 proteins to human caspase motifs.
Conclusions:
- Wheat PR-1 proteins possess distinct dimerization and protease resistance characteristics.
- Specific residues within the PR-1 domain are crucial for dimerization and protease resistance.
- Findings suggest a potential role for PR-1 proteins in protease-mediated programmed cell death in plants.
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