Journal Article

Natural Genome Diversity of AI-2 Quorum Sensing in <i>Escherichia coli</i>: Conserved Signal Production but Labile Signal Reception

Patrícia H. Brito, Eduardo P.C. Rocha, Karina B. Xavier and Isabel Gordo

in Genome Biology and Evolution

Published on behalf of Society for Molecular Biology and Evolution

Volume 5, issue 1, pages 16-30
Published in print January 2013 |
Published online December 2012 | e-ISSN: 1759-6653 | DOI: http://dx.doi.org/10.1093/gbe/evs122

More Like This

Show all results sharing these subjects:

  • Bioinformatics and Computational Biology
  • Evolutionary Biology
  • Genetics and Genomics

GO

Show Summary Details

Preview

Quorum sensing (QS) regulates the onset of bacterial social responses in function to cell density having an important impact in virulence. Autoinducer-2 (AI-2) is a signal that has the peculiarity of mediating both intra- and interspecies bacterial QS. We analyzed the diversity of all components of AI-2 QS across 44 complete genomes of Escherichia coli and Shigella strains. We used phylogenetic tools to study its evolution and determined the phenotypes of single-deletion mutants to predict phenotypes of natural strains. Our analysis revealed many likely adaptive polymorphisms both in gene content and in nucleotide sequence. We show that all natural strains possess the signal emitter (the luxS gene), but many lack a functional signal receptor (complete lsr operon) and the ability to regulate extracellular signal concentrations. This result is in striking contrast with the canonical species-specific QS systems where one often finds orphan receptors, without a cognate synthase, but not orphan emitters. Our analysis indicates that selection actively maintains a balanced polymorphism for the presence/absence of a functional lsr operon suggesting diversifying selection on the regulation of signal accumulation and recognition. These results can be explained either by niche-specific adaptation or by selection for a coercive behavior where signal-blind emitters benefit from forcing other individuals in the population to haste in cooperative behaviors.

Keywords: genome evolution; gene loss; E. coli; balancing selection; social cheater; bacteria signaling

Journal Article.  8914 words.  Illustrated.

Subjects: Bioinformatics and Computational Biology ; Evolutionary Biology ; Genetics and Genomics

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.