Crystal structure of RimI from Salmonella typhimurium LT2, the GNAT responsible for Nα-acetylation of ribosomal protein S18

Matthew W. Vetting, David C. Bareich, Michael Yu, John S. Blanchard

Research output: Contribution to journalArticlepeer-review

59 Scopus citations


The three ribosomal proteins L7, S5, and S18 are included in the rare subset of prokaryotic proteins that are known to be Nα- acetylated. The GCN5-related N-acetyltransferase (GNAT) protein RimI, responsible for the Nα-acetylation of the ribosomal protein S18, was cloned from Salmonella typhimurium LT2 (RimIST), overexpressed, and purified to homogeneity. Steady-state kinetic parameters for RimIST were determined for AcCoA and a peptide substrate consisting of the first six amino acids of the target protein S18. The crystal structure of RimIST was determined in complex with CoA, AcCoA, and a CoA-S-acetyl-ARYFRR bisubstrate inhibitor. The structures are consistent with a direct nucleophilic addition-elimination mechanism with Glu103 and Tyr115 acting as the catalytic base and acid, respectively. The RimIST-bisubstrate complex suggests that several residues change conformation upon interacting with the N terminus of S18, including Glu103, the proposed active site base, facilitating proton exchange and catalysis.

Original languageEnglish (US)
Pages (from-to)1781-1790
Number of pages10
JournalProtein Science
Issue number10
StatePublished - Oct 2008


  • Bisubstrate inhibition
  • GNAT structure
  • Protein N-acetylation
  • Ribosomal protein

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology


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