Proteasomes Accumulate in the Plant Apoplast Where They Participate in Microbe-Associated Molecular Pattern (MAMP)-Triggered Pathogen Defense

ABSTRACT: Akin to mammalian extracellular fluids, the plant apoplastic fluid (APF) contains a unique collection of proteins, RNAs, and vesicles that drive many physiological processes ranging from cell wall assembly to defense against environmental challenges. Using an improved method to enrich for the Arabidopsis APF, we better defined its composition and discovered that the APF harbors active proteasomes though microscopic detection, proteasome-specific activity and immunological assays, and mass spectrometry showing selective enrichment of the core protease. Functional analysis of extracellular (ex)-proteasomes revealed that they help promote basal pathogen defense through proteolytic release of microbe-associated molecular patterns (MAMPs) such as flg22 from bacterial flagellin that induce protective reactive-oxygen-species (ROS) bursts. Flagellin-triggered ROS is also strongly suppressed by the enigmatic Pseudomonas syringae virulence effector syringolin-A that blocks ex-proteasome activity. Collectively, we provide a deep catalog of apoplast proteins and evidence that ex-proteasomes participate in the evolving arms race between pathogens and their plant hosts.

INSTRUMENT(S): Q Exactive HF

ORGANISM(S): Arabidopsis Thaliana (mouse-ear Cress)

TISSUE(S): Plant Cell, Whole Body

SUBMITTER: Kuo-En Chen  

LAB HEAD: Richard D. Vierstra

PROVIDER: PXD059522 | Pride | 2025-01-08

REPOSITORIES: pride