Structural similarity of tailed phages and pathogenic bacterial secretion systems

A Common Evolutionary Origin for Tailed-Bacteriophage Functional Modules and Bacterial Machineries

“…Hence, pathogenic bacteria appear to have acquired the structural components of tailed bacteriophages in order to develop secretion systems that are crucial elements in support of their pathogenicity (36). Moreover, the accumulated data on bacteriophage tails and the T6SS support the idea that a single ancestral tail tube protein has yielded most of the proteins required to form a tube or a needle assembly by duplication events followed by specialization resulting from genetic exchange through insertions/deletions.…”

Structural Insights into the Pseudomonas aeruginosa Type VI Virulence Effector Tse1 Bacteriolysis and Self-protection Mechanisms

“…Two conserved T6SS components, hemolysin co-regulated protein and valine-glycine repeat protein G, have been structurally characterized and have remarkable homology to bacteriophage tail proteins (10 -12). These findings prompt the speculation that T6SS may assemble as an inverted phage tail across the envelope of bacteria, targeting bacterial cells by a puncturing manner analogous to bacteriophage entry (13,14). However, the mechanism underlying effector delivery through this secretory apparatus and the functions of the effectors in recipient cells remain unclear.…”

Structural Characterization and Oligomerization of the TssL Protein, a Component Shared by Bacterial Type VI and Type IVb Secretion Systems

“…VgrG assembles as trimers resembling the bacteriophage gp27/gp5 complex (7,21,22). Recently, electron microscopy studies have proposed that the TssB and TssC proteins form structures resembling the bacteriophage sheath (21,23,24) From these observations and the structural similarities of TssE with the bacteriophage baseplate component gp25 (1), a model on how the T6SS is structurally arranged and how it functions has recently emerged (25,26). It has been proposed that the T6SS forms an inverted bacteriophage-like structure that will puncture the target cell to deliver the protein effectors.…”