Xanthomonas effector XopR hijacks host actin cytoskeleton via complex coacervation

Area of Science:

• Plant pathology
• Molecular biology
• Biochemistry

Background:

• Intrinsically disordered regions (IDRs) are key features of phytobacterial type III effectors (T3Es).
• IDRs are believed to facilitate effector translocation and immune evasion through sequence variation.
• The precise mechanisms by which T3Es manipulate host cells remain an active area of research.

Purpose of the Study:

• To elucidate the mechanism by which the Xanthomonas campestris T3E XopR subverts the host actin cytoskeleton.
• To investigate the role of the T3E IDR in host-pathogen interactions.

Main Methods:

• Studied liquid-liquid phase separation (LLPS) of XopR mediated by its IDR.
• Investigated the interaction of XopR with the Arabidopsis actin cytoskeleton and actin-binding proteins.
• Analyzed the manipulation of actin assembly dynamics, including nucleation, crosslinking, and depolymerization.

Main Results:

• XopR undergoes LLPS via multivalent IDR interactions, forming coacervates.
• XopR hijacks the Arabidopsis actin cytoskeleton by forming macromolecular complexes at the cell cortex.
• XopR progressively manipulates actin nucleation, F-actin crosslinking, and actin depolymerization through stoichiometric control of coacervates.

Conclusions:

• Bacterial T3Es employ sophisticated strategies, such as protein complex coacervation, to subvert host cellular processes.
• The IDR of XopR is crucial for hijacking the host actin cytoskeleton, enabling bacterial virulence.