Activity profiling of vacuolar processing enzymes reveals a role for VPE during oomycete infection

Area of Science:

• Plant biochemistry
• Molecular plant pathology
• Protease activity profiling

Background:

• Vacuolar processing enzymes (VPEs) are crucial cysteine proteases involved in plant development, programmed cell death, and plant-microbe interactions.
• Understanding VPE activity is key to elucidating these complex biological processes.

Purpose of the Study:

• To develop and validate a specific, cell-permeable activity-based probe for VPEs.
• To investigate the role of VPE activity in plant responses to pathogen infection.

Main Methods:

• Synthesis and characterization of a novel VPE activity-based probe.
• In vivo imaging of VPE activity in various plant tissues and species.
• Analysis of VPE activity during infection with Hyaloperonospora arabidopsidis (Hpa).
• Assessment of Hpa sporulation in VPE mutant plants.

Main Results:

• The developed probe is highly specific for all four Arabidopsis VPEs and exhibits activity-dependent labeling.
• In vivo imaging revealed diverse active VPE isoforms across plant tissues and species.
• VPE activity significantly increased during Hpa infection, originating from the host and independent of EDS1.
• Reduced Hpa sporulation was observed in vpe mutant plants, indicating a role for VPE in compatible interactions.

Conclusions:

• VPE activity profiling is a powerful tool for plant research, enabling visualization of enzyme activity in vivo.
• Increased host VPE activity during Hpa infection benefits the pathogen, likely by facilitating nutrient acquisition.
• VPEs play a role in compatible plant-pathogen interactions, potentially independent of programmed cell death.