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Local structural differences between alpha- and beta-elicitins shown by circular dichroism and ultraviolet difference
1Department of Plant Physiology and Biochemistry, INRA Versailles, France.
International Journal of Peptide and Protein Research
|February 1, 1994
Summary
Differences in elicitin conformation were studied using spectroscopy. Beta-elicitins, more toxic than alpha-elicitins, show distinct tyrosyl residue environments, influencing their activity.
Area of Science:
- Protein structure and function
- Spectroscopic analysis of biological molecules
- Plant-pathogen interactions
Background:
- Elicitins are proteins involved in plant defense.
- Alpha- and beta-elicitins display varying toxicity levels.
- Understanding structural differences can explain activity variations.
Purpose of the Study:
- To investigate conformational differences in elicitins with varying toxicity.
- To compare the tyrosyl residue environments in alpha- and beta-elicitins.
- To correlate structural features with elicitin activity.
Main Methods:
- Spectroscopic methods including difference absorption and circular dichroism.
- Thermal difference UV spectroscopy.
- Titration experiments to determine pK values.
Main Results:
- Tyrosyl residues Tyr-85 and Tyr-87 are exposed at the surface in some elicitins.
- Beta-elicitins exhibit a more exposed tyrosine (attributed to Tyr-12) compared to alpha-elicitins.
- Differences in local environments affect tyrosyl residue pK values, with parasiticein showing a higher pK.
Conclusions:
- Structural variations in tyrosyl residue environments correlate with elicitin toxicity.
- The exposed Tyr-12 in beta-elicitins may contribute to their higher toxicity.
- Specific tyrosines (Tyr-47, Tyr-33) have distinct accessibility and titration behaviors across different elicitins.