A Bacterial Effector Mimics a Host HSP90 Client to Undermine Immunity

Area of Science:

• Molecular Biology
• Plant Pathology
• Immunology

Background:

• Heat shock protein 90 (HSP90) is crucial for plant and animal immunity.
• Pathogenic strategies targeting HSP90 have not been previously identified.

Purpose of the Study:

• To identify bacterial effector proteins that target HSP90.
• To elucidate the mechanism by which bacterial pathogens manipulate host immunity via HSP90.

Main Methods:

• Identification and characterization of HopBF1 effector proteins.
• Biochemical assays to assess HSP90 ATPase activity and phosphorylation.
• Plant infection assays with Pseudomonas syringae.

Main Results:

• The HopBF1 family of bacterial effectors are eukaryotic-specific HSP90 protein kinases.
• HopBF1 phosphorylates HSP90, inhibiting its ATPase activity and preventing immune receptor activation.
• HopBF1-induced HSP90 inhibition leads to severe disease symptoms in plants.

Conclusions:

• HopBF1 effectors represent a novel class of bacterial toxins targeting host HSP90.
• Bacterial pathogens can betray host immunity by hijacking HSP90 function.
• This study reveals a new mechanism of host immune modulation by bacterial pathogens.