AUTHOR=How Kah Yan , Hong Kar-Wai , Sam Choon-Kook , Koh Chong-Lek , Yin Wai-Fong , Chan Kok-Gan 

TITLE=Unravelling the genome of long chain N-acylhomoserine lactone-producing Acinetobacter sp. strain GG2 and identification of its quorum sensing synthase gene

JOURNAL=Frontiers in Microbiology

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2015.00240

DOI=10.3389/fmicb.2015.00240

ISSN=1664-302X

ABSTRACT=<p>Myriad proteobacteria use <italic>N</italic>-acyl homoserine lactone (AHL) molecules as quorum sensing (QS) signals to regulate different physiological functions, including virulence, antibiotic production, and biofilm formation. Many of these proteobacteria possess LuxI/LuxR system as the QS mechanism. Recently, we reported the 3.89 Mb genome of <italic>Acinetobacter</italic> sp. strain GG2. In this work, the genome of this long chain AHL-producing bacterium was unravelled which led to the molecular characterization of <italic>luxI</italic> homologue, designated as <italic>aciI</italic>. This 552 bp gene was cloned and overexpressed in <italic>Escherichia coli</italic> BL21(DE3). The purified protein was ∼20.5 kDa and is highly similar to several autoinducer proteins of LuxI family among <italic>Acinetobacter</italic> species. To verify the AHL synthesis activity of this protein, high-resolution liquid chromatography–mass spectrometry analysis revealed the production of 3-oxo-dodecanoyl-homoserine lactone and 3-hydroxy-dodecanoyl-homoserine lactone from induced <italic>E. coli</italic> harboring the recombinant AciI. Our data show for the first time, the cloning and characterization of the <italic>luxI</italic> homologue from <italic>Acinetobacter</italic> sp. strain GG2, and confirmation of its AHLs production. These data are of great significance as the annotated genome of strain GG2 has provided a valuable insight in the study of autoinducer molecules and its roles in QS mechanism of the bacterium.</p>