HopZ4 from Pseudomonas syringae, a member of the HopZ type III effector family from the YopJ superfamily, inhibits the proteasome.
The YopJ-family of type III effector (T3E) proteins is one of the largest and widely distributed families of effector proteins whose members are highly diversified in virulence functions. In the present study, HopZ4, a member of the YopJ-family of T3Es from the cucumber pathogen Pseudomonas syringae pv. lachrymans is described. HopZ4 shares high sequence similarity with the Xanthomonas T3E XopJ and a functional analysis suggests a conserved virulence function between these two T3Es. As has previously shown for XopJ, HopZ4 interacts with the proteasomal subunit RPT6 in yeast and in planta to inhibit proteasome activity during infection. The inhibitory effect on the proteasome is dependent on localization of HopZ4 to the plasma membrane as well as on an intact catalytic triad of the effector protein. Furthermore, HopZ4 is able to complement loss of XopJ in Xanthomonas as it prevents precocious host cell death during a compatible interaction of Xanthomonas with pepper. The data presented here suggest that different bacterial species employ inhibition of the proteasome as a virulence strategy by making use of conserved T3Es from the YopJ-family of bacterial effector proteins.
Üstün, S.; König, P.; Gutmann, D.S.; Börnke, F. 2014. HopZ4 from Pseudomonas syringae, a member of the HopZ type III effector family from the YopJ superfamily, inhibits the proteasome. Molecular Plant-Microbe Interactions 27 (7) 611-623.