Comparing the modeled structures of PR-4 proteins from wheat

Area of Science:

• Structural biology
• Plant pathology
• Biochemistry

Background:

• Pathogenesis-related (PR) proteins are crucial in plant defense mechanisms.
• The PR-4 family, including wheat proteins (wheatwins), plays a role in plant immunity.
• Understanding the structural basis of PR protein function is key to developing crop protection strategies.

Purpose of the Study:

• To construct and analyze three-dimensional models of four wheat PR-4 proteins (wheatwins).
• To investigate the correlation between structural differences in wheatwins and their antifungal activity.
• To identify specific protein regions potentially involved in the antifungal action mechanism.

Main Methods:

• Comparative three-dimensional modeling of wheat PR-4 proteins based on homologous barley protein (barwin) structure.
• Analysis of amino acid variations and their impact on secondary and tertiary structures.
• Prediction of exposed/hidden traits and correlation with experimentally determined antifungal activity against Fusarium culmorum.

Main Results:

• High structural similarity was observed among the four wheatwin models, despite minor amino acid substitutions.
• Key differences were identified in exposed traits (15-21, 84-86) and a hidden trait (91-93), with varying secondary structure predictions.
• Distinct antifungal activities of wheatwins against Fusarium culmorum were observed and strongly correlated with these structural variations.

Conclusions:

• Specific structural regions (traits 15-21, 84-86, and 91-93) in wheat PR-4 proteins are critical determinants of antifungal activity.
• These identified regions likely play a significant role in the yet unknown action mechanism of wheat PR-4 proteins.
• The findings provide insights into structure-function relationships of plant defense proteins, aiding in the development of novel antifungal strategies.