Type III secretion system effector HopBF1 kinase domain
This entry represents the kinase domain of the Type III secretion system effector HopBF1, which functions as an atypical bacterial protein kinase that targets and inactivates eukaryotic HSP90 molecular chaperones. HopBF1 adopts a minimal protein kina ...
This entry represents the kinase domain of the Type III secretion system effector HopBF1, which functions as an atypical bacterial protein kinase that targets and inactivates eukaryotic HSP90 molecular chaperones. HopBF1 adopts a minimal protein kinase fold lacking the typical C-terminal GHI helical subdomain found in canonical kinases. The protein is secreted via the type III secretion system into host cells where it phosphorylates a conserved serine residue in the HSP90 ATP binding site (Ser99 in yeast, Ser108 in human HSP90-beta), inhibiting the chaperone's ATPase activity. HopBF1 mimics an HSP90 client to achieve specificity by interacting with HSP90 through the alpha C-beta 4 loop that contains conserved hydrophobic residues. This effector is found in various phytopathogenic bacteria including Pseudomonas syringae where it prevents activation of plant immune receptors that trigger the hypersensitive response.
