Structural basis for arginine glycosylation of host substrates by bacterial effector proteins

Nat Commun. 2018 Oct 16;9(1):4283. doi: 10.1038/s41467-018-06680-6.

Abstract

The bacterial effector proteins SseK and NleB glycosylate host proteins on arginine residues, leading to reduced NF-κB-dependent responses to infection. Salmonella SseK1 and SseK2 are E. coli NleB1 orthologs that behave as NleB1-like GTs, although they differ in protein substrate specificity. Here we report that these enzymes are retaining glycosyltransferases composed of a helix-loop-helix (HLH) domain, a lid domain, and a catalytic domain. A conserved HEN motif (His-Glu-Asn) in the active site is important for enzyme catalysis and bacterial virulence. We observe differences between SseK1 and SseK2 in interactions with substrates and identify substrate residues that are critical for enzyme recognition. Long Molecular Dynamics simulations suggest that the HLH domain determines substrate specificity and the lid-domain regulates the opening of the active site. Overall, our data suggest a front-face SNi mechanism, explain differences in activities among these effectors, and have implications for future drug development against enteric pathogens.

Publication types

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

MeSH terms

  • Acetylglucosamine / metabolism
  • Animals
  • Arginine / chemistry
  • Arginine / metabolism*
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Catalytic Domain
  • Crystallography, X-Ray
  • Escherichia coli Proteins / chemistry
  • Female
  • Glycosylation
  • HEK293 Cells
  • Host-Pathogen Interactions / physiology*
  • Humans
  • Mice, Inbred BALB C
  • Molecular Dynamics Simulation
  • Nuclear Magnetic Resonance, Biomolecular
  • Salmonella typhimurium / pathogenicity
  • Substrate Specificity
  • Virulence Factors / chemistry

Substances

  • Bacterial Proteins
  • Escherichia coli Proteins
  • NleB protein, E coli
  • SseK1 protein, Salmonella enterica
  • SseK2 protein, Salmonella enterica
  • Virulence Factors
  • Arginine
  • Acetylglucosamine