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The C-terminal domain is sufficient for host-binding activity of the Mu phage tail-spike protein

Hidetaka Suzuki1, Seiko Yamada, Yoshiharu Toyama

  • 1Department of Chemical Biology, Graduate School of Engineering, Gunma, University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515, Japan.

Biochimica Et Biophysica Acta
|May 19, 2010
PubMed

Insights

The Mu phage tail spike protein (gp45) C-terminal domain irreversibly binds to E. coli membranes, functioning similarly to other phage tail spikes despite lacking sequence homology.

Area of Science:

  • Microbiology
  • Structural Biology
  • Biochemistry

Background:

  • Bacteriophages, like Mu phage, utilize tail-spike proteins for host cell adsorption.
  • Gene product 45 (gp45) constitutes the tail spikes of Mu phage, essential for infecting Escherichia coli.

Purpose of the Study:

  • To identify the functional and structural domains of the Mu phage tail-spike protein (gp45).
  • To characterize the biophysical properties and membrane-binding capabilities of gp45 domains.

Main Methods:

  • Purification and characterization of full-length and C-terminal domains of recombinant gp45.
  • Limited proteolysis to isolate stable protein domains.
  • Analytical ultracentrifugation to determine molecular weight and oligomeric state.
  • Coprecipitation assays and quartz crystal microbalance (QCM) to assess membrane binding.

Main Results:

  • A stable C-terminal domain (gp45-C, Ser64-Gln197) was identified.
  • Analytical ultracentrifugation revealed gp45-C forms a stable trimeric protomer (approx. 58 kDa).
  • Coprecipitation and QCM confirmed irreversible binding of gp45-C to the E. coli membrane.

Conclusions:

  • The C-terminal domain of Mu phage gp45 is crucial for its interaction with the E. coli outer membrane.
  • gp45 exhibits functional similarities to other characterized phage tail-spike proteins.
  • Mu phage gp45 represents a novel structural class of phage tail spikes, lacking significant sequence homology with known structures.

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