PABP/purine-rich motif as an initiation module for cap-independent translation in pattern-triggered immunity

Cell. 2022 Aug 18;185(17):3186-3200.e17. doi: 10.1016/j.cell.2022.06.037. Epub 2022 Jul 30.


Upon stress, eukaryotes typically reprogram their translatome through GCN2-mediated phosphorylation of the eukaryotic translation initiation factor, eIF2α, to inhibit general translation initiation while selectively translating essential stress regulators. Unexpectedly, in plants, pattern-triggered immunity (PTI) and response to other environmental stresses occur independently of the GCN2/eIF2α pathway. Here, we show that while PTI induces mRNA decapping to inhibit general translation, defense mRNAs with a purine-rich element ("R-motif") are selectively translated using R-motif as an internal ribosome entry site (IRES). R-motif-dependent translation is executed by poly(A)-binding proteins (PABPs) through preferential association with the PTI-activating eIFiso4G over the repressive eIF4G. Phosphorylation by PTI regulators mitogen-activated protein kinase 3 and 6 (MPK3/6) inhibits eIF4G's activity while enhancing PABP binding to the R-motif and promoting eIFiso4G-mediated defense mRNA translation, establishing a link between PTI signaling and protein synthesis. Given its prevalence in both plants and animals, the PABP/R-motif translation initiation module may have a broader role in reprogramming the stress translatome.

Keywords: IRES; MPK3/MPK6; PABP; R-motif; RACK1; cap-independent translation; eIF4G; eIFiso4G; pattern-triggered immunity; translational reprogramming.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Eukaryotic Initiation Factor-4G* / genetics
  • Eukaryotic Initiation Factor-4G* / metabolism
  • Eukaryotic Initiation Factors / metabolism
  • Poly(A)-Binding Proteins* / metabolism
  • Protein Biosynthesis
  • Purines
  • RNA, Messenger / metabolism


  • Eukaryotic Initiation Factor-4G
  • Eukaryotic Initiation Factors
  • Poly(A)-Binding Proteins
  • Purines
  • RNA, Messenger