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Identification of a Key Amino Acid of LuxS Involved in AI-2 Production in Campylobacter jejuni
PLoS One
  • Paul J. Plummer, Iowa State University
  • Jinge Zhu, Ohio State University
  • Masato Akiba, Iowa State University
  • Dehua Pei, Ohio State University
  • Qijing Zhang, Iowa State University
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Autoinducer-2 (AI-2) mediated quorum sensing has been associated with the expression of virulence factors in a number of pathogenic organisms and has been demonstrated to play a role in motility and cytolethal distending toxin (cdt) production in Campylobacter jejuni. We have initiated the work to determine the molecular basis of AI-2 synthesis and the biological functions of quorum sensing in C. jejuni. In this work, two naturally occurring variants of C. jejuni 81116 were identified, one producing high-levels of AI-2 while the other is defective in AI-2 synthesis. Sequence analysis revealed a G92D mutation in the luxS gene of the defective variant. Complementation of the AI-2− variant with a plasmid encoded copy of the wild-typeluxS gene or reversion of the G92D mutation by site-directed mutagenesis fully restored AI-2 production by the variant. These results indicate that the G92D mutation alone is responsible for the loss of AI-2 activity in C. jejuni. Kinetic analyses showed that the G92D LuxS has a ∼100-fold reduced catalytic activity relative to the wild-type enzyme. Findings from this study identify a previously undescribed amino acid that is essential for AI-2 production by LuxS and provide a unique isogenic pair of naturally occurring variants for us to dissect the functions of AI-2 mediated quorum sensing in Campylobacter.

This article is from PLoS One 6 (2011): e15876, doi:10.1371/journal.pone.0015876. Posted with permission.

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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Paul J. Plummer, et al
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Paul J. Plummer, Jinge Zhu, Masato Akiba, Dehua Pei, et al.. "Identification of a Key Amino Acid of LuxS Involved in AI-2 Production in Campylobacter jejuni" PLoS One Vol. 61 Iss. 1 (2011) p. e15876
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