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Type VI secretion system sheath inter-subunit interactions modulate its contraction.

Maximilian Brackmann1, Jing Wang1, Marek Basler2

  • 1Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland.

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|December 10, 2017
PubMed
Summary
This summary is machine-generated.

Modifying bacterial type VI secretion system (T6SS) components prevents sheath contraction, halting effector delivery. This discovery offers insights into T6SS pre-firing mechanisms.

Keywords:
contractile tailsmicrobiologyphagestype VI secretion system

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Area of Science:

  • Microbiology
  • Molecular Biology
  • Structural Biology

Background:

  • Bacterial secretion systems are vital for survival and environmental interaction.
  • The type VI secretion system (T6SS) utilizes a contractile sheath for protein translocation.
  • The precise mechanism of T6SS sheath contraction remains poorly understood.

Purpose of the Study:

  • To investigate the mechanism of T6SS sheath contraction.
  • To identify key residues and structural elements involved in T6SS function.
  • To explore the potential for controlling T6SS activity.

Main Methods:

  • Genetic manipulation of T6SS components (VipA linker elongation, VipB residue charge alteration).
  • Observation of sheath contraction and effector delivery.
  • Mass spectrometry to identify associated proteins in non-contractile sheaths.

Main Results:

  • Altering the VipA linker or VipB charge abolished sheath contraction.
  • Effector delivery into target cells was blocked in modified T6SS.
  • Mass spectrometry identified inner tube (Hcp), spike (VgrG), and baseplate proteins in stable, non-contractile sheaths.

Conclusions:

  • Specific modifications to VipA and VipB are critical for T6SS sheath contraction.
  • The study provides a method to lock the T6SS in a pre-firing state.
  • This offers new avenues for studying T6SS mechanism and function.