double-psi beta-barrel fold of the kiwellin family
Kiwellin (KWL) proteins comprise a widespread family of plant-defense proteins that target pathogenic bacterial/fungal effectors that down-regulate plant defense responses. They are part of a spatio-temporally coordinated, plant-wide defense response comprising KWL proteins with overlapping activities. Zea mays KWL1 specifically inhibits the enzymatic activity of the secreted chorismate mutase Cmu1, a virulence-promoting effector of the smut fungus Ustilago maydis. KWL proteins adopt a double-psi beta-barrel (DPBB) fold, which provides a versatile scaffold that can specifically counteract pathogen effectors such as Cmu1.