Type VI secretion (T6S) influences the composition of microbial communities by catalyzing the delivery of toxins between adjacent bacterial cells.

Authors in the journal Cell demonstrate that a T6S integral membrane toxin from Pseudomonas aeruginosa, Tse6, acts on target cells by degrading the universally essential dinucleotides NAD⁺ and NADP⁺.

Authors find that entry of Tse6 into target cells requires its binding to an essential housekeeping protein, translation elongation factor Tu (EF-Tu). These proteins participate in a larger assembly that additionally directs toxin export and provides chaperone activity.

Visualization of this complex by electron microscopy defines the architecture of a toxin-loaded T6S apparatus and provides mechanistic insight into intercellular membrane protein delivery between bacteria.

http://www.cell.com/cell/abstract/S0092-8674(15)01189-7