Quorum Sensing Attenuates Virulence in Sodalis praecaptivus

Publication date: 10 May 2017
Source:Cell Host & Microbe, Volume 21, Issue 5
Author(s): Shinichiro Enomoto, Abhishek Chari, Adam Larsen Clayton, Colin Dale
Sodalis praecaptivus is a close relative and putative environmental progenitor of the widely distributed, insect-associated, Sodalis-allied symbionts. Here we show that mutant strains of S. praecaptivus that lack genetic components of a quorum-sensing (QS) apparatus have a rapid and potent killing phenotype following microinjection into an insect host. Transcriptomic and genetic analyses indicate that insect killing occurs as a consequence of virulence factors, including insecticidal toxins and enzymes that degrade the insect integument, which are normally repressed by QS at high infection densities. This method of regulation suggests that virulence factors are only utilized in early infection to initiate the insect-bacterial association. Once bacteria reach sufficient density in host tissues, the QS circuit represses expression of these harmful genes, facilitating a long-lasting and benign association. We discuss the implications of the functionality of this QS system in the context of establishment and evolution of mutualistic relationships involving these bacteria.

Graphical abstract

Teaser

Enomoto et al. show that a progenitor of the widely distributed Sodalis-allied insect endosymbionts utilizes quorum sensing to suppress virulence factors following the establishment of infection. This allows bacteria to maintain a benign and persistent infection in their insect host, possibly facilitating the evolution of mutualistic relationships.


http://ift.tt/2r4e1hX