Calcium-induced membrane microdomains trigger plant phospholipase D activity

Area of Science:

• Biochemistry
• Plant Biology
• Enzymology

Background:

• Plant alpha-type phospholipase D (PLD) are calcium-dependent enzymes.
• Enzyme-substrate interaction is influenced by substrate aggregate morphology.
• Understanding PLD regulation is crucial for plant cellular processes.

Purpose of the Study:

• To investigate the role of membrane microdomains in plant alpha-type PLD activation.
• To elucidate the mechanism by which Ca(2+) influences PLD activity.
• To identify key factors regulating PLD-phospholipid interactions.

Main Methods:

• Utilized vesicles composed of POPC and POPA lipids.
• Employed Ca(2+) ions to induce microdomain formation.
• Assessed PLD activity using lag phase analysis and film balance measurements.
• Analyzed lipid phase behavior with differential scanning calorimetry.

Main Results:

• A 500-fold stimulation of white cabbage PLDalpha was observed with 10 mol% POPA incorporation into POPC vesicles and Ca(2+).
• Enhanced PLDalpha2 association with anionic lipid surfaces (POPA) was detected.
• POPA-specific activation correlated with Ca(2+)-induced changes in vesicle phase behavior.

Conclusions:

• Ca(2+)-induced formation of POPA microdomains is critical for PLD binding to phospholipid surfaces.
• This microdomain formation acts as a cellular switch to control PLD activity.
• Findings provide insights into the regulation of plant phospholipase D enzymes.