Int. J. Mol. Sci. 2013, 14(10), 20578-20596; doi:10.3390/ijms141020578
Article

Structural Insights into a Novel Interkingdom Signaling Circuit by Cartography of the Ligand-Binding Sites of the Homologous Quorum Sensing LuxR-Family

1 Institute of Crystallography, National Research Council, Trieste Outstation, Area Science Park-Basovizza, S.S. n° 14 Km 163.5, I-34149 Trieste, Italy 2 International Centre for Genetic Engineering and Biotechnology, Padriciano 99, I-34149 Trieste, Italy 3 IBIOBA-CONICET-ICGEB, International Centre for Genetic Engineering and Biotechnology, Scientific and Technological Center, Godoy Cruz 2390, C1425FQD, Buenos Aires, Argentina
* Authors to whom correspondence should be addressed.
Received: 1 August 2013; in revised form: 13 September 2013 / Accepted: 1 October 2013 / Published: 15 October 2013
(This article belongs to the Special Issue Quorum Sensing Research in Microbial Systems)
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Abstract: Recent studies have identified a novel interkingdom signaling circuit, via plant signaling molecules, and a bacterial sub-family of LuxR proteins, bridging eukaryotes and prokaryotes. Indeed pivotal plant-bacteria interactions are regulated by the so called Plant Associated Bacteria (PAB) LuxR solo regulators that, although closely related to the quorum sensing (QS) LuxR family, do not bind or respond to canonical quorum sensing N-acyl homoserine lactones (AHLs), but only to specific host plant signal molecules. The large body of structural data available for several members of the QS LuxR family complexed with different classes of ligands (AHLs and other compounds), has been exploited to dissect the cartography of their regulatory domains through structure-based multiple sequence alignments, structural superimposition and a comparative analysis of the contact residues involved in ligand binding. In the absence of experimentally determined structures of members of the PAB LuxR solos subfamily, an homology model of its prototype OryR is presented, aiming to elucidate the architecture of its ligand-binding site. The obtained model, in combination with the cartography of the regulatory domains of the homologous QS LuxRs, provides novel insights into the 3D structure of its ligand-binding site and unveils the probable molecular determinants responsible for differences in selectivity towards specific host plant signal molecules, rather than to canonical QS compounds.
Keywords: quorum sensing; bacterial-plant communication; interkingdom signaling; Plant Associated Bacteria LuxR solos; ligand binding site; molecular modeling; structure-based multiple alignment

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MDPI and ACS Style

Covaceuszach, S.; Degrassi, G.; Venturi, V.; Lamba, D. Structural Insights into a Novel Interkingdom Signaling Circuit by Cartography of the Ligand-Binding Sites of the Homologous Quorum Sensing LuxR-Family. Int. J. Mol. Sci. 2013, 14, 20578-20596.

AMA Style

Covaceuszach S, Degrassi G, Venturi V, Lamba D. Structural Insights into a Novel Interkingdom Signaling Circuit by Cartography of the Ligand-Binding Sites of the Homologous Quorum Sensing LuxR-Family. International Journal of Molecular Sciences. 2013; 14(10):20578-20596.

Chicago/Turabian Style

Covaceuszach, Sonia; Degrassi, Giuliano; Venturi, Vittorio; Lamba, Doriano. 2013. "Structural Insights into a Novel Interkingdom Signaling Circuit by Cartography of the Ligand-Binding Sites of the Homologous Quorum Sensing LuxR-Family." Int. J. Mol. Sci. 14, no. 10: 20578-20596.

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