Three-dimensional structure of tropism-switching Bordetella bacteriophage

Wei Dai, Asher Hodes, Wong H. Hui, Mari Gingery, Jeff F. Miller, Z. Hong Zhou

Research output: Contribution to journalArticlepeer-review

51 Scopus citations

Abstract

Bacteriophage BPP-1, which infects Bordetella species, can switch its specificity by mutations to the ligand-binding surface of its major tropism-determinant protein, Mtd. This targeted mutagenesis results from the activity of a phage-encoded diversity-generating retroelement. Purified Mtd binds its receptor with low affinity, yet BPP-1 binding and infection of Bordettella cells are efficient because of high-avidity binding between phage-associated Mtd and its receptor. Here, using an integrative approach of three-dimensional (3D) structural analyses of the entire phage by cryo-electron tomography and single-prticle cryo-electron microscopy, we provide direct localization of Mtd in the phage and the structural basis of the high-avidity binding of the BPP-1 phage. Our structure shows that each BPP-1 particle has a T = 7 icosahedral head and an unusual tail apparatus consisting of a short central tail "hub," six short tail spikes, and six extended tail fibers. Subtomographic averaging of the tail fiber maps revealed a two-lobed globular structure at the distal end of each long tail fiber. Tomographic reconstructions of immuno-gold-labeled BPP-1 directly localized Mtd to these globular structures. Finally, our icosahedral reconstruction of the BPP-1 head at 7Å resolution reveals an HK97-like major capsid protein stabilized by a smaller cementing protein. Our structure represents a unique bacteriophage reconstruction with its tail fibers and ligand-binding domains shown in relation to its tail apparatus. The localization of Mtd at the distal ends of the six tail fibers explains the high avidity binding of Mtd molecules to cell surfaces for initiation of infection.

Original languageEnglish (US)
Pages (from-to)4347-4352
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume107
Issue number9
DOIs
StatePublished - Mar 2 2010

All Science Journal Classification (ASJC) codes

  • General

Keywords

  • Avidity
  • Bordetella phage
  • Cryo-electron microscopy
  • Tropism-determinant protein

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