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An intersubunit active site between supercoiled parallel beta helices in the trimeric tailspike endorhamnosidase of

Jürgen J Müller1, Stefanie Barbirz, Karolin Heinle

  • 1Max-Delbrück-Centrum für Molekulare Medizin, Robert-Rössle-Str. 10, 13125 Berlin, Germany.

Structure (London, England : 1993)
|May 9, 2008
PubMed

Insights

Shigella phage Sf6 tailspike protein (Sf6 TSP) has a unique beta-helix structure. This structure facilitates binding to Shigella O-antigen, offering insights into phage-host interactions and evolution.

Area of Science:

  • Microbiology
  • Structural Biology
  • Virology

Background:

  • Temperate bacteriophages like Sf6 infect gram-negative bacteria via tailspike proteins.
  • Understanding phage-host interactions is crucial for molecular biology and biotechnology.

Purpose of the Study:

  • To determine the crystal structure of Shigella phage Sf6 tailspike protein (Sf6 TSP).
  • To elucidate the mechanism of Sf6 TSP binding to its host.
  • To compare Sf6 TSP with related bacteriophage tailspike proteins.

Main Methods:

  • X-ray crystallography (1.25 A resolution).
  • Biochemical analyses.
  • Structural comparison with P22 TSP.

Main Results:

  • Sf6 TSP exhibits a conserved architecture with a central, right-handed beta helix forming a left-handed coiled-beta coil in its trimer.
  • A Shigella O-antigen fragment binds to an endorhamnosidase active site located between two beta-helix subunits.
  • Sf6 TSP shows no sequence identity to the related P22 TSP, which has active sites on single subunits.

Conclusions:

  • Sf6 TSP possesses a unique structural and functional mechanism for host binding.
  • The study provides a model for understanding the evolution of host specificity in bacteriophages.
  • Sf6 TSP structure reveals insights into viral capsid protein similarities and enzyme active site formation.

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