title: Citrus limonoids interfere with Vibrio harveyi cell-cell signalling and biofilm formation by modulating the response regulator LuxO.
abstract: Citrus limonoids are unique secondary metabolites, characterized by a triterpenoid skeleton with a furan ring. Studies have demonstrated beneficial health properties of limonoids. In addition, certain citrus limonoids play a role in plant defence against insect pests. In the present study, five limonoids were purified from sour orange and evaluated for their ability to inhibit cell-cell signalling. The purified limonoids were tested for their ability to interfere with cell-cell signalling and biofilm formation in Vibrio harveyi. Isolimonic acid, deacetylnomilinic acid glucoside and ichangin demonstrated significant inhibition of autoinducer-mediated cell-cell signalling and biofilm formation. Furthermore, isolimonic acid and ichangin treatment resulted in induced expression of the response regulator gene luxO. In addition, luxR promoter activity was not affected by isolimonic acid or ichangin. Therefore, the ability of isolimonic acid and ichangin to interfere with cell-cell signalling and biofilm formation seems to stem from the modulation of luxO expression. The results suggest that isolimonic acid and ichangin are potent modulators of bacterial cell-cell signalling.
authors.affiliation: Vegetable and Fruit Improvement Center, Department of Horticultural Sciences, Texas A&M University, College Station, TX 77843, USA.
authors.forename: Amit
authors.initials: A
authors.lastname: Vikram
authors.affiliation: Food Safety and Environmental Microbiology Program, Texas A&M University, College Station, TX 77843, USA.
authors.forename: Palmy R
authors.initials: PR
authors.lastname: Jesudhasan
authors.affiliation: Vegetable and Fruit Improvement Center, Department of Horticultural Sciences, Texas A&M University, College Station, TX 77843, USA.
authors.forename: G K
authors.initials: GK
authors.lastname: Jayaprakasha
authors.affiliation: Food Safety and Environmental Microbiology Program, Texas A&M University, College Station, TX 77843, USA.|Vegetable and Fruit Improvement Center, Department of Horticultural Sciences, Texas A&M University, College Station, TX 77843, USA.
authors.forename: Suresh D
authors.initials: SD
authors.lastname: Pillai
authors.affiliation: Vegetable and Fruit Improvement Center, Department of Horticultural Sciences, Texas A&M University, College Station, TX 77843, USA.
authors.forename: Bhimanagouda S
authors.initials: BS
authors.lastname: Patil
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis*; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D002957:Citrus / Q000737:chemistry*; D015870:Gene Expression; D036701:Limonins / Q000302:isolation & purification / Q000378:metabolism*; D053038:Quorum Sensing / Q000187:drug effects*; D012097:Repressor Proteins / Q000096:biosynthesis*; D015854:Up-Regulation; D014733:Vibrio / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; D036701:Limonins; C088907:LuxO protein, Vibrio harveyi; D012097:Repressor Proteins