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Action of a minimal contractile bactericidal nanomachine.

  • Author(s): Ge, Peng
  • Scholl, Dean
  • Prokhorov, Nikolai S
  • Avaylon, Jaycob
  • Shneider, Mikhail M
  • Browning, Christopher
  • Buth, Sergey A
  • Plattner, Michel
  • Chakraborty, Urmi
  • Ding, Ke
  • Leiman, Petr G
  • Miller, Jeff F
  • Zhou, Z Hong
  • et al.
Abstract

R-type bacteriocins are minimal contractile nanomachines that hold promise as precision antibiotics1-4. Each bactericidal complex uses a collar to bridge a hollow tube with a contractile sheath loaded in a metastable state by a baseplate scaffold1,2. Fine-tuning of such nucleic acid-free protein machines for precision medicine calls for an atomic description of the entire complex and contraction mechanism, which is not available from baseplate structures of the (DNA-containing) T4 bacteriophage5. Here we report the atomic model of the complete R2 pyocin in its pre-contraction and post-contraction states, each containing 384 subunits of 11 unique atomic models of 10 gene products. Comparison of these structures suggests the following sequence of events during pyocin contraction: tail fibres trigger lateral dissociation of baseplate triplexes; the dissociation then initiates a cascade of events leading to sheath contraction; and this contraction converts chemical energy into mechanical force to drive the iron-tipped tube across the bacterial cell surface, killing the bacterium.

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