title: Genetic and phenotypic analysis of the GacS/GacA system in the moderate halophile Halomonas anticariensis.
abstract: A multisensory, hybrid histidine kinase (HK) and a response regulator (RR), which together may well constitute a two-component regulatory system (TCS), have been located in Halomonas anticariensis FP35(T) by transposon mutagenesis. This TCS is homologous to the GacS/GacA system described for many Gram-negative bacteria. An analysis of crude N-acylhomoserine lactone (AHL) extracts from cultures of FP35gacS and FP35gacA mutants showed that they produced lower quantities of AHLs than the wild-type strain. In addition, RT-PCR analysis revealed a considerable decrease in the expression of the quorum-sensing (QS) genes hanR and hanI compared with the wild-type strain. This result indicates that the GacS/GacA TCS exerts a positive effect upon the QS HanR/HanI system and suggests its integral involvement in the intercellular communication strategies of this bacterium. We have also demonstrated the influence of GacS and GacA upon exopolysaccharide production and biofilm formation, in which this regulatory machinery appears to play a key role in an overall system that co-ordinates gene expression and behaviour in H. anticariensis FP35(T) in response to environmental conditions.
authors.affiliation: Department of Microbiology, Faculty of Pharmacy, University of Granada, Campus Universitario de Cartuja, 18071 Granada, Spain.
authors.forename: Ali
authors.initials: A
authors.lastname: Tahrioui
authors.affiliation: Biotechnology Research Institute, Polígono Universitario de Fuentenueva, University of Granada, 18071 Granada, Spain.|Department of Microbiology, Faculty of Pharmacy, University of Granada, Campus Universitario de Cartuja, 18071 Granada, Spain.
authors.forename: Emilia
authors.initials: E
authors.lastname: Quesada
authors.affiliation: Biotechnology Research Institute, Polígono Universitario de Fuentenueva, University of Granada, 18071 Granada, Spain.|Department of Microbiology, Faculty of Pharmacy, University of Granada, Campus Universitario de Cartuja, 18071 Granada, Spain.
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Llamas
mesh_terms: D054742:Acyl-Butyrolactones / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D020869:Gene Expression Profiling; D055786:Gene Knockout Techniques; D020632:Halomonas / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D000071677:Histidine Kinase; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D011135:Polysaccharides, Bacterial / Q000378:metabolism; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D053038:Quorum Sensing; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D054742:Acyl-Butyrolactones; D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; C091100:GacA protein, Bacteria; D011135:Polysaccharides, Bacterial; D011494:Protein Kinases; D000071677:Histidine Kinase