A role for S-nitrosylation of the SUMO-conjugating enzyme SCE1 in plant immunity

Michael Skelly, Saad Malik, Thierry Le Bihan, Yuan Bo, Jihong Jiang, Steven Spoel, Gary Loake

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

SUMOylation, the covalent attachment of the small ubiquitin-like modifier (SUMO) to target proteins, is emerging as a key modulator of eukaryotic immune function. In plants, a SUMO1/2-dependent process has been proposed to control the deployment of host defense responses. The molecular mechanism underpinning this activity remains to be determined, however. Here we show that increasing nitric oxide levels following pathogen recognition promote S-nitrosylation of the Arabidopsis SUMO E2 enzyme, SCE1, at Cys139. The SUMO-conjugating activities of both SCE1 and its human homolog, UBC9, were inhibited following this modification. Accordingly, mutation of Cys139 resulted in increased levels of SUMO1/2 conjugates, disabled immune responses, and enhanced pathogen susceptibility. Our findings imply that S-nitrosylation of SCE1 at Cys139 enables NO bioactivity to drive immune activation by relieving SUMO1/2-mediated suppression. The control of global SUMOylation is thought to occur predominantly at the level of each substrate via complex local machineries. Our findings uncover a parallel and complementary mechanism by suggesting that total SUMO conjugation may also be regulated directly by SNO formation at SCE1 Cys139. This Cys is evolutionary conserved and specifically S-nitrosylated in UBC9, implying that this immune-related regulatory process might be conserved across phylogenetic kingdoms.
Original languageEnglish
Pages (from-to)17090-17095
Number of pages6
JournalProceedings of the National Academy of Sciences (PNAS)
Issue number34
Early online date1 Aug 2019
Publication statusPublished - 20 Aug 2019

Keywords / Materials (for Non-textual outputs)

  • nitric oxide
  • S-nitrosylation
  • immunity


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