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Updated: Jul 14, 2025

A Visual Assay to Monitor T6SS-mediated Bacterial Competition
Published on: March 20, 2013
The tip protein PAAR is required for the function of the type VI secretion system
Solène G Beauvois1, Nicolas Flaugnatti1, Marianne Ilbert2
1Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie, Bioénergies et Biotechnologie, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université - CNRS UMR7255 , Marseille, France.
Importance:
The type VI secretion system (T6SS) is a bacterial contractile injection system involved in bacterial competition by the delivery of antibacterial toxins. The T6SS consists of an envelope-spanning complex that recruits the baseplate, allowing the polymerization of a contractile tail structure. The tail is a tube wrapped by a sheath and topped by the tip of the system, the VgrG spike/PAAR complex. Effectors loaded onto the puncturing tip or into the tube are propelled in the target cells upon sheath contraction. The PAAR protein tips and sharpens the VgrG spike. However, the importance and the function of this protein remain unclear. Here, we provide evidence for association of PAAR at the tip of the VgrG spike. We also found that the PAAR protein is a T6SS critical component required for baseplate and sheath assembly.
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