Advancing evolution: Bacteria break down gene silencer to express horizontally acquired genes

Bioessays. 2023 Oct;45(10):e2300062. doi: 10.1002/bies.202300062. Epub 2023 Aug 3.

Abstract

Horizontal gene transfer advances bacterial evolution. To benefit from horizontally acquired genes, enteric bacteria must overcome silencing caused when the widespread heat-stable nucleoid structuring (H-NS) protein binds to AT-rich horizontally acquired genes. This ability had previously been ascribed to both anti-silencing proteins outcompeting H-NS for binding to AT-rich DNA and RNA polymerase initiating transcription from alternative promoters. However, we now know that pathogenic Salmonella enterica serovar Typhimurium and commensal Escherichia coli break down H-NS when this silencer is not bound to DNA. Curiously, both species use the same protease - Lon - to destroy H-NS in distinct environments. Anti-silencing proteins promote the expression of horizontally acquired genes without binding to them by displacing H-NS from AT-rich DNA, thus leaving H-NS susceptible to proteolysis and decreasing H-NS amounts overall. Conserved amino acid sequences in the Lon protease and H-NS cleavage site suggest that diverse bacteria degrade H-NS to exploit horizontally acquired genes.

Keywords: Lon; PhoP; heat-stable nucleoid-structuring protein; horizontal gene transfer; transcription.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Bacteria / metabolism
  • Bacterial Proteins* / genetics
  • Bacterial Proteins* / metabolism
  • DNA-Binding Proteins* / genetics
  • DNA-Directed RNA Polymerases / genetics
  • Gene Expression Regulation, Bacterial / genetics
  • Salmonella typhimurium / genetics
  • Salmonella typhimurium / metabolism

Substances

  • DNA-Binding Proteins
  • Bacterial Proteins
  • DNA-Directed RNA Polymerases