1. Academic Validation
  2. N-Terminal Acetylation Stabilizes SIGMA FACTOR BINDING PROTEIN1 Involved in Salicylic Acid-Primed Cell Death

N-Terminal Acetylation Stabilizes SIGMA FACTOR BINDING PROTEIN1 Involved in Salicylic Acid-Primed Cell Death

  • Plant Physiol. 2020 May;183(1):358-370. doi: 10.1104/pp.19.01417.
Zihao Li 1 2 Vivek Dogra 1 Keun Pyo Lee 1 Rongxia Li 1 Mingyue Li 1 2 Mengping Li 1 2 Chanhong Kim 3
Affiliations

Affiliations

  • 1 Shanghai Center for Plant Stress Biology and Center of Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
  • 2 University of the Chinese Academy of Sciences, Beijing 100049, China.
  • 3 Shanghai Center for Plant Stress Biology and Center of Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China chanhongkim@sibs.ac.cn.
Abstract

N-terminal (Nt) acetylation (NTA) is an ample and irreversible cotranslational protein modification catalyzed by ribosome-associated Nt-acetyltransferases. NTA on specific proteins can act as a degradation signal (called an Ac/N-degron) for proteolysis in yeast and mammals. However, in Plants, the biological relevance of NTA remains largely unexplored. In this study, we reveal that Arabidopsis (Arabidopsis thaliana) SIGMA FACTOR-BINDING PROTEIN1 (SIB1), a transcription coregulator and a positive regulator of salicylic acid-primed cell death, undergoes an absolute NTA on the initiator Met; Nt-acetyltransferase B (NatB) partly contributes to this modification. While NTA results in destabilization of certain target proteins, our genetic and biochemical analyses revealed that plant NatB-involved NTA instead renders SIB1 more stable. Given that the ubiquitin/Proteasome system stimulates SIB1 degradation, it seems that the NTA-conferred stability ensures the timely expression of SIB1-dependent genes, mostly related to immune responses. Taking our findings together, here we report a noncanonical NTA-driven protein stabilization in land Plants.

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