Two serine residues in Pseudomonas syringae effector HopZ1a are required for acetyltransferase activity and association with the host co‐factor

Abstract

Summary Gram-negative bacteria inject type III secreted effectors (T3SEs) into host cells to manipulate the immune response. The YopJ family effector HopZ1a produced by the plant pathogen Pseudomonas syringae possesses acetyltransferase activity and acetylates plant proteins to facilitate infection.Using mass spectrometry, we identified a threonine residue, T346, as the main autoacetylation site of HopZ1a. Two neighboring serine residues, S349 and S351, are required for the acetyltransferase activity of HopZ1a in vitro and are indispensable for the virulence function of HopZ1a in Arabidopsis thaliana.Using proton nuclear magnetic resonance (NMR), we observed a conformational change of HopZ1a in the presence of inositol hexakisphosphate (IP6), which acts as a eukaryotic co-factor and significantly enhances the acetyltransferase activity of several YopJ family effectors. S349 and S351 are required for IP6-binding-mediated conformational change of HopZ1a.S349 and S351 are located in a conserved region in the C-terminal domain of YopJ family effectors. Mutations of the corresponding serine(s) in two other effectors, HopZ3 of P. syringae and PopP2 of Ralstonia solanacerum, also abolished their acetyltransferase activity. These results suggest that, in addition to the highly conserved catalytic residues, YopJ family effectors also require conserved serine(s) in the C-terminal domain for their enzymatic activity.

Plant-Pathogen Effectors: Cellular Probes Interfering with Plant Defenses in Spatial and Temporal Manners

“…HopZ1a is an acetyltransferase and acetylates both soybean and Arabidopsis JAZ proteins, leading to their degradation (52). Transgenic Arabidopsis plants expressing HopZ1a are also able to suppress stomatal defense (74). The P. syringae effector HopM1 suppresses stomatal defense by targeting the Arabidopsis 14-3-3 protein GRF8/AtMIN10 (68).…”

Behind the lines–actions of bacterial type III effector proteins in plant cells

“…2012; Ma et al. 2015). It remains to be investigated whether the acetylation of JAZ proteins by HopZ1a facilitates their COI1-dependent degradation.…”

Stomatal Defense a Decade Later

“…AvrB enhances the interaction of RIN4 and AHA1, which could promote the interaction between COI1 and JAZs, leading to stomatal opening Lee et al, 2015). HopX1 and HopZ1 induce stomatal opening after PTI-mediated stomatal closure, through a COI1-independent and COI1-dependent manner, respectively (Jiang et al, 2013;Gimenez-Ibanez et al, 2014;Ma et al, 2015). XopR interacts with BIK1 and suppresses stomatal closure possibly by inhibition of RBOHD (Wang et al, 2016).…”

“…HopZ1 possesses acetyltransferase activity, directly interacts with JAZ proteins, and promotes JAZ acetylation and degradation to activate JA signaling in soybean and Arabidopsis (Jiang et al, 2013). Moreover, HopZ1 can induce stomatal opening after flg22-mediate stomatal closure in Arabidopsis (Ma et al, 2015). Finally, the HopX1 Cys protease effector from P. syringae pv tabaci (which also does not produce COR) can interact with and promote degradation of JAZ proteins, in a COI1-independent manner, resulting in stomatal opening (Gimenez-Ibanez et al, 2014).…”