Structure and properties of the c-terminal β-helical domain of vgrg protein from escherichia coli O157

Kazuya Uchida, Petr G. Leiman, Fumio Arisaka, Shuji Kanamaru

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


The bacterial Type 6 secretion system (T6SS) translocates protein toxins (also called effectors) from the cytosol of a T6SS-carrying cell to a target cell by a syringe-like supramolecular complex resembling a contractile tail of bacteriophages. Valine-glycine repeat protein G (VgrG) proteins, which are the homologues of the gp27-gp5 (gene product) cell puncturing complex of bacteriophage T4, are considered to be located at the attacking tip of the bacterial T6SS apparatus. Here, we over-expressed six VgrG proteins from pathogenic Escherichia coli O157 and CFT073 strains. Purified VgrG1 of E. coli O157 and c3393 of E. coli CFT073 form trimer in solution and are rich in β-structure. We also solved the crystal structure of a trypsin-resistant C-terminal fragment of E. coli O157 VgrG1 (VgrG1CG561) at 1.95 Å resolution. VgrG1CG561 forms a three-stranded antiparallel β-helix which is structurally similar to the β-helix domain of the central spike protein (gp138) of phi92 phage, indicating a possible evolutional relationship. Comparison of four different three-stranded β-helix proteins shows how their amino acid composition determines the protein fold.

Original languageEnglish (US)
Pages (from-to)173-182
Number of pages10
JournalJournal of Biochemistry
Issue number3
StatePublished - Mar 2014
Externally publishedYes


  • Type 6 secretion system
  • X-ray crystallography
  • bacteria
  • structure
  • three-stranded β-helix

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology


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