N-terminomics identifies Prli42 as a membrane miniprotein conserved in Firmicutes and critical for stressosome activation in Listeria monocytogenes

Nat Microbiol. 2017 Feb 13:2:17005. doi: 10.1038/nmicrobiol.2017.5.

Abstract

To adapt to changing environments, bacteria have evolved numerous pathways that activate stress response genes. In Gram-positive bacteria, the stressosome, a cytoplasmic complex, relays external cues and activates the sigma B regulon. The stressosome is structurally well-characterized in Bacillus, but how it senses stress remains elusive. Here, we report a genome-wide N-terminomic approach in Listeria that strikingly led to the discovery of 19 internal translation initiation sites and 6 miniproteins, among which one, Prli42, is conserved in Firmicutes. Prli42 is membrane-anchored and interacts with orthologues of Bacillus stressosome components. We reconstituted the Listeria stressosome in vitro and visualized its supramolecular structure by electron microscopy. Analysis of a series of Prli42 mutants demonstrated that Prli42 is important for sigma B activation, bacterial growth following oxidative stress and for survival in macrophages. Taken together, our N-terminonic approach unveiled Prli42 as a long-sought link between stress and the stressosome.

MeSH terms

  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism*
  • Firmicutes / genetics*
  • Firmicutes / metabolism
  • Gene Expression Regulation, Bacterial*
  • Genome, Bacterial
  • Listeria monocytogenes / genetics*
  • Listeria monocytogenes / metabolism
  • Membranes / chemistry
  • Membranes / metabolism
  • Protein Processing, Post-Translational / genetics
  • Proteomics / methods
  • Regulon / genetics
  • Sigma Factor / genetics
  • Signal Transduction
  • Stress, Physiological / genetics*

Substances

  • Bacterial Proteins
  • Sigma Factor