An Intersubunit Active Site between Supercoiled Parallel β Helices in the Trimeric Tailspike Endorhamnosidase of Shigella flexneri Phage Sf6

Jürgen J. Müller, Stefanie Barbirz, Karolin Heinle, Alexander Freiberg, Robert Seckler, Udo Heinemann

Research output: Contribution to journalArticle

55 Scopus citations


Sf6 belongs to the Podoviridae family of temperate bacteriophages that infect gram-negative bacteria by insertion of their double-stranded DNA. They attach to their hosts specifically via their tailspike proteins. The 1.25 Å crystal structure of Shigella phage Sf6 tailspike protein (Sf6 TSP) reveals a conserved architecture with a central, right-handed β helix. In the trimer of Sf6 TSP, the parallel β helices form a left-handed, coiled-β coil with a pitch of 340 Å. The C-terminal domain consists of a β sandwich reminiscent of viral capsid proteins. Further crystallographic and biochemical analyses show a Shigella cell wall O-antigen fragment to bind to an endorhamnosidase active site located between two β-helix subunits each anchoring one catalytic carboxylate. The functionally and structurally related bacteriophage, P22 TSP, lacks sequence identity with Sf6 TSP and has its active sites on single subunits. Sf6 TSP may serve as an example for the evolution of different host specificities on a similar general architecture.

Original languageEnglish (US)
Pages (from-to)766-775
Number of pages10
Issue number5
StatePublished - May 7 2008
Externally publishedYes




ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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