Bacterial effectors target the common signaling partner BAK1 to disrupt multiple MAMP receptor-signaling complexes and impede plant immunity.
Successful pathogens have evolved strategies to interfere with host immune systems. For example, the ubiquitous plant pathogen Pseudomonas syringae injects two sequence-distinct effectors, AvrPto and AvrPtoB, to intercept convergent innate immune responses stimulated by multiple microbe-associated molecular patterns (MAMPs). However, the direct host targets and precise molecular mechanisms of bacterial effectors remain largely obscure. We show that AvrPto and AvrPtoB bind the Arabidopsis receptor-like kinase BAK1, a shared signaling partner of both the flagellin receptor FLS2 and the brassinosteroid receptor BRI1. This targeting interferes with ligand-dependent association of FLS2 with BAK1 during infection. It also impedes BAK1-dependent host immune responses to diverse other MAMPs and brassinosteroid signaling. Significantly, the structural basis of AvrPto-BAK1 interaction appears to be distinct from AvrPto-Pto association required for effector-triggered immunity. These findings uncover a unique strategy of bacterial pathogenesis where virulence effectors block signal transmission through a key common component of multiple MAMP-receptor complexes.
Shan
Libo
L
Department of Molecular Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. shan@molbio.mgh.harvard.edu
He
Ping
P
Li
Jianming
J
Heese
Antje
A
Peck
Scott C
SC
Nürnberger
Thorsten
T
Martin
Gregory B
GB
Sheen
Jen
J
D017360:Arabidopsis / Q000276:immunology* / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D047468:Immunoprecipitation; D008954:Models, Biological; D030821:Plants, Genetically Modified; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D025941:Protein Interaction Mapping; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D044224:Pseudomonas syringae / Q000472:pathogenicity*; D015398:Signal Transduction; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
D029681:Arabidopsis Proteins; D001426:Bacterial Proteins; D037521:Virulence Factors; C081695:avrPto protein, Pseudomonas syringae; D011494:Protein Kinases; C463660:BAK1 protein, Arabidopsis; C411853:FLS2 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases