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Infectious polymorphic toxins delivered by outer membrane exchange discriminate kin in myxobacteria

Christopher N Vassallo1, Pengbo Cao1, Austin Conklin1

  • 1Department of Molecular Biology, University of Wyoming, Laramie, United States.

Elife
|August 19, 2017
PubMed

Insights

Myxobacteria use novel SitA toxins delivered via outer membrane exchange (OME) to distinguish kin. These toxins spread cell-to-cell, reinforcing social behaviors and strain diversity.

Area of Science:

  • Microbiology
  • Bacterial social behavior
  • Genetics

Background:

  • Myxobacteria exhibit complex social behaviors, including outer membrane exchange (OME), a process mediated by the TraA receptor.
  • OME involves the exchange of lipids and proteins between bacterial cells.
  • Current understanding suggests TraA receptor polymorphism is insufficient for precise kin discrimination.

Purpose of the Study:

  • To identify novel mechanisms myxobacteria use for kin discrimination during OME.
  • To characterize a new family of toxins involved in regulating OME interactions.
  • To understand the role of these toxins in bacterial social structure and evolution.

Main Methods:

  • Identification and characterization of the SitA toxin family and associated genes (sitI, sitB).
  • Analysis of SitA toxin polymorphism and distribution across myxobacteria.
  • Experimental demonstration of SitA toxin transfer between bacterial cells.

Main Results:

  • A novel family of OME-delivered, polymorphic lipoprotein toxins, named SitA, was discovered.
  • Each sitA gene is linked to a cognate sitI immunity gene and sometimes a sitB accessory gene.
  • SitA toxins are serially transferred between cells, functioning akin to infectious agents and establishing strong inter-strain barriers.

Conclusions:

  • SitA toxins are crucial for precise kin discrimination in myxobacteria during OME.
  • These toxins likely play a significant role in maintaining cooperation, population structure, and strain diversification.
  • The findings reveal a diverse strategy for inter-bacterial toxin delivery in prokaryotes.
Keywords:
Myxococcus xanthusinfectiousinfectious diseasekin discriminationmicrobiologymyxobacteriaself-recognitiontoxins

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