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Cell Host Microbe. 2017 May 10;21(5):629-636.e5. doi: 10.1016/j.chom.2017.04.003.

Quorum Sensing Attenuates Virulence in Sodalis praecaptivus.

Author information

1
Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, UT 84112, USA.
2
Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, UT 84112, USA. Electronic address: colin.dale@utah.edu.

Abstract

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.

KEYWORDS:

insect; insecticidal toxin; quorum sensing; symbiosis; virulence

PMID:
28494244
PMCID:
PMC5542680
DOI:
10.1016/j.chom.2017.04.003
[Indexed for MEDLINE]
Free PMC Article

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