Identification of New N‐Acylhomoserine Lactone Signalling Compounds of Dinoroseobacter shibae DFL‐12T by Overexpression of luxI Genes |
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Authors: | Alexander Neumann Diana Patzelt Prof. Dr. Irene Wagner‐Döbler Prof. Dr. Stefan Schulz |
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Affiliation: | 1. Technische Universit?t Braunschweig, Institut für Organische Chemie, Hagenring 30, 38106 Braunschweig (Germany);2. Helmholtz Institute for Infection Research, Division of Cell Biology, Group Microbial Communication, Mascheroder Weg 1, 38124 Braunschweig (Germany) |
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Abstract: | Bacteria of the Roseobacter clade are widespread in the ocean and occur in many different habitats. In the genome of Dinoroseobacter shibae DFL‐12, luxI homologous genes that encode synthases responsible for the formation of N‐acylhomoserine lactones (AHLs) have been described. These compounds are known autoinducers that regulate several biological traits—namely, flagella formation and cell differentiation—in D. shibae through quorum sensing. The AHLs produced by D. shibae mainly consisted of N‐octadecadienoylhomoserine lactone (C18:2‐AHL) and N‐octadecenoylhomoserine lactone (C18:1‐HSL). In the wild type these AHLs are synthesized only in low abundance. The luxI genes were therefore expressed in Escherichia coli; this resulted in the formation of AHLs mostly different from those found in the D. shibae wild type. A luxI1‐deficient mutant of D. shibae was then reprovided with an overexpressed luxI1 gene. This strain produced large amounts of C18:2‐AHL and C18:1‐AHL, allowing full characterization of these compounds by mass spectrometric techniques and derivatization. Synthesis of the proposed structures confirmed that the major compound is (2E,11Z)‐N‐octadeca‐2,11‐dienoylhomoserine lactone ( 6 , C18:2‐HSL), accompanied by (Z)‐N‐octadec‐11‐enoylhomoserine lactone ( 5 , C18:1‐HSL). AHL 6 has not been reported before from other organisms and contains an unusual 2E double bond. |
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Keywords: | bacteria chemical communication gas chromatography mass spectrometry quorum sensing |
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