Cell
Volume 179, Issue 1, 19 September 2019, Pages 205-218.e21
Journal home page for Cell

Article
A Bacterial Effector Mimics a Host HSP90 Client to Undermine Immunity

https://doi.org/10.1016/j.cell.2019.08.020Get rights and content
Under an Elsevier user license
open archive

Highlights

  • The bacterial effector HopBF1 adopts a minimal protein kinase fold

  • HopBF1 phosphorylates and inactivates eukaryotic HSP90

  • HopBF1 mimics an HSP90 client to achieve specificity

  • HopBF1 is sufficient to induce disease symptoms in plants

Summary

The molecular chaperone HSP90 facilitates the folding of several client proteins, including innate immune receptors and protein kinases. HSP90 is an essential component of plant and animal immunity, yet pathogenic strategies that directly target the chaperone have not been described. Here, we identify the HopBF1 family of bacterial effectors as eukaryotic-specific HSP90 protein kinases. HopBF1 adopts a minimal protein kinase fold that is recognized by HSP90 as a host client. As a result, HopBF1 phosphorylates HSP90 to completely inhibit the chaperone’s ATPase activity. We demonstrate that phosphorylation of HSP90 prevents activation of immune receptors that trigger the hypersensitive response in plants. Consequently, HopBF1-dependent phosphorylation of HSP90 is sufficient to induce severe disease symptoms in plants infected with the bacterial pathogen, Pseudomonas syringae. Collectively, our results uncover a family of bacterial effector kinases with toxin-like properties and reveal a previously unrecognized betrayal mechanism by which bacterial pathogens modulate host immunity.

Keywords

HSP90
phosphorylation
chaperone
immunity
kinase
HopBF1
Pseudomonas syringae
effector

Cited by (0)

10

These authors contributed equally

11

Lead Contact