The Arabidopsis E3 ubiquitin ligase PUB4 regulates BIK1 homeostasis and is targeted by a bacterial type-III effector

Derkacheva, M.; Yu, G.; Rufian, J. S.; Jiang, S.; Derbyshire, P.; Morcillo, R.; Stransfeld, L.; Wei, Y.; Menke, F.; Zipfel, C.; Macho, A.

doi:10.1101/2020.10.25.354514

bioRxiv · 10.1101/2020.10.25.354514

The Arabidopsis E3 ubiquitin ligase PUB4 regulates BIK1 homeostasis and is targeted by a bacterial type-III effector

Derkacheva, M.·Yu, G.·Rufian, J. S.·Jiang, S.·Derbyshire, P.·Morcillo, R.·Stransfeld, L.·Wei, Y.·Menke, F.·Zipfel, C.·Macho, A.

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Abstract

Plant immunity is tightly controlled by a complex and dynamic regulatory network, which ensures optimal activation upon detection of potential pathogens. Accordingly, each component of this network is a potential target for manipulation by pathogens. Here, we report that RipAC, a type III-secreted effector from the bacterial pathogen Ralstonia solanacearum, targets the plant E3 ubiquitin ligase PUB4 to inhibit pattern-triggered immunity (PTI). PUB4 plays a positive role in PTI by regulating the homeostasis of the central immune kinase BIK1. Before PAMP perception, PUB4 promotes the degradation of non-activated BIK1, while, after PAMP perception, PUB4 contributes to the accumulation of activated BIK1. RipAC leads to BIK1 degradation, which correlates with its PTI-inhibitory activity. RipAC causes a reduction in pathogen-associated molecular pattern (PAMP)-induced PUB4 accumulation and phosphorylation. Our results shed light on the role played by PUB4 in immune regulation, and illustrate an indirect targeting of the immune signalling hub BIK1 by a bacterial effector.

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Derkacheva, M., Yu, G., Rufian, J. S., Jiang, S., Derbyshire, P., Morcillo, R., Stransfeld, L., Wei, Y., Menke, F., Zipfel, C., Macho, A.. 2020-10-26. The Arabidopsis E3 ubiquitin ligase PUB4 regulates BIK1 homeostasis and is targeted by a bacterial type-III effector. https://doi.org/10.1101/2020.10.25.354514

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