Inhibition of SRP-dependent protein secretion by the bacterial alarmone (p)ppGpp

Nat Commun. 2022 Feb 25;13(1):1069. doi: 10.1038/s41467-022-28675-0.

Abstract

The stringent response enables bacteria to respond to nutrient limitation and other stress conditions through production of the nucleotide-based second messengers ppGpp and pppGpp, collectively known as (p)ppGpp. Here, we report that (p)ppGpp inhibits the signal recognition particle (SRP)-dependent protein targeting pathway, which is essential for membrane protein biogenesis and protein secretion. More specifically, (p)ppGpp binds to the SRP GTPases Ffh and FtsY, and inhibits the formation of the SRP receptor-targeting complex, which is central for the coordinated binding of the translating ribosome to the SecYEG translocon. Cryo-EM analysis of SRP bound to translating ribosomes suggests that (p)ppGpp may induce a distinct conformational stabilization of the NG domain of Ffh and FtsY in Bacillus subtilis but not in E. coli.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / metabolism
  • Escherichia coli / metabolism
  • Escherichia coli Proteins* / metabolism
  • Guanosine Pentaphosphate / metabolism
  • Protein Binding
  • Receptors, Cytoplasmic and Nuclear / metabolism
  • Signal Recognition Particle* / metabolism

Substances

  • Bacterial Proteins
  • Escherichia coli Proteins
  • Receptors, Cytoplasmic and Nuclear
  • Signal Recognition Particle
  • Guanosine Pentaphosphate