Histone-Like Protein H-NS as a Negative Regulator of Quorum Sensing Systems in Gram-Negative Bacteria

The effects of histone-like protein H-NS on transcription of promoters of the Quorum Sensing regulated operons from marine luminescent mesophilic bacterium Aliivibrio fischeri and psychrophilic Aliivibrio logei, as well as from pathogenic Pseudomonas aeruginosa, are studied. In the present work, the plasmids carrying DNA fragments with the promoters P-r1f (upstream of the luxICDABEG operon from A. fischeri), P-r11 (upstream of the luxCDABEG operon from A. logei), P-r21 (upstream of luxI gene from A. logei), P-luxCf (upstream of luxC gene from A. fischeri), and P-las1 (upstream of lasI gene from P. aerugenosa) are used. In these plasmids, promoter-operator regions are transcriptionally fused to the reporter genes cassette luxC-DABE from Photorhabdus luminescens. Here we have shown that the transcription of the QS-regulated promoters in E. coli hns::kan cells increases 100 to 1000 times. Furthermore, transcription of the QS-regulated promoters in E. coli hns(+) cells increases 10 to 100 times in the cells transformed with the plasmid carrying gene ardA Co1Ib-P9 encoding DNA mimic antirestriction protein ArdA, inhibitor of the type I restriction-modification systems.