J Integr Plant Biol. ›› 2023, Vol. 65 ›› Issue (6): 1585-1601.DOI: 10.1111/jipb.13461

• Plant Biotic Interactions • Previous Articles    

Phosphorylation of the LCB1 subunit of Arabidopsis serine palmitoyltransferase stimulates its activity and modulates sphingolipid biosynthesis

Yuan Li1†, Hanwei Cao1†, Tingting Dong1†, Xiaoke Wang2, Liang Ma1, Kun Li3, Huiqiang Lou2, Chun-Peng Song3 and Dongtao Ren1*   

  1. 1. State Key Laboratory of Plant Environmental Resilience, College of Biological Sciences, China Agricultural University, Beijing 100193, China
    2. State Key Laboratory of Agro-Biotechnology and Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Biological Sciences, China Agricultural University, Beijing 100193, China
    3. Collaborative Innovation Center of Crop Stress Biology, Henan Province. Institute of Plant Stress Biology, School of Life Science, Henan University, Kaifeng 475001, China
    These authors contributed equally to this work
    *Correspondence:Dongtao Ren(ren@cau.edu.cn)
  • Received:2022-10-10 Accepted:2023-02-02 Online:2023-02-04 Published:2023-06-01

Abstract: Sphingolipids are the structural components of membrane lipid bilayers and act as signaling molecules in many cellular processes. Serine palmitoyltransferase (SPT) is the first committed and rate-limiting enzyme in the de novo sphingolipids biosynthetic pathway. The core SPT enzyme is a heterodimer consisting of LONG-CHAIN BASE1 (LCB1) and LCB2 subunits. SPT activity is inhibited by orosomucoid proteins and stimulated by small subunits of SPT (ssSPTs). However, whether LCB1 is modified and how such modification might regulate SPT activity have to date been unclear. Here, we show that activation of MITOGEN-ACTIVATED PROTEIN KINASE 3 (MPK3) and MPK6 by upstream MKK9 and treatment with Flg22 (a pathogen-associated molecular pattern) increases SPT activity and induces the accumulation of sphingosine long-chain base t18:0 in Arabidopsis thaliana, with activated MPK3 and MPK6 phosphorylating AtLCB1. Phosphorylation of AtLCB1 strengthened its binding with AtLCB2b, promoted its binding with ssSPTs, and stimulated the formation of higher order oligomeric and active SPT complexes. Our findings therefore suggest a novel regulatory mechanism for SPT activity.

Key words: Arabidopsis, MAPK, phosphorylation, sphingolipids

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