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Sci Rep

Title:		Comparative analysis reveals regulatory motifs at the ainS/ainR pheromone-signaling locus of Vibrio fischeri
Author(s):		Kimbrough JH; Stabb EV;
Address:		"Department of Microbiology, University of Georgia, Athens, GA, USA. Department of Microbiology, University of Georgia, Athens, GA, USA. estabb@uga.edu"
Journal Title:		Sci Rep
Year:		2017
Volume:		20170915
Issue:		1
Page Number:		11734 -
DOI:		10.1038/s41598-017-11967-7
ISSN/ISBN:		2045-2322 (Electronic) 2045-2322 (Linking)
Abstract:		"Vibrio fischeri uses the AinS/AinR pheromone-signaling system to control bioluminescence and other symbiotic colonization factors. The Ain system is thought to initiate cell-cell signaling at moderate cell densities and to prime the LuxI/LuxR signaling system. Here we compared and analyzed the ain locus from two V. fischeri strains and a Vibrio salmonicida strain to explore ain regulation. The ainS and ainR genes were predicted to constitute an operon, which we corroborated using RT-PCR. Comparisons between strains revealed a stark area of conservation across the ainS-ainR junction, including a large inverted repeat in ainR. We found that this inverted repeat in cis can affect accumulation of the AinS-generated pheromone N-octanoyl homoserine lactone, which may account for the previously unexplained low-signal phenotype of a ?OsainR mutant, although the mechanism behind this regulation remains elusive. We also extended the previous observation of a possible 'lux box' LuxR binding site upstream of ainS by showing the conservation of this site as well as a second putative lux box. Using a plasmid-based reporter we found that LuxR can mediate repression of ainS, providing a negative feedback mechanism in the Ain/Lux signaling cascade. Our results provide new insights into the regulation, expression, and evolution of ainSR"
Keywords:		"Aliivibrio fischeri/genetics/*physiology Bacterial Proteins/*physiology Cell Communication Feedback, Physiological/*physiology Gene Expression Regulation, Bacterial Genes, Regulator Luminescence Repressor Proteins/physiology *Signal Transduction Species S;"
Notes:		"MedlineKimbrough, John H Stabb, Eric V eng Comparative Study Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. England 2017/09/17 Sci Rep. 2017 Sep 15; 7(1):11734. doi: 10.1038/s41598-017-11967-7"