title: Membrane Topology and Structural Insights into the Peptide Pheromone Receptor ComD, A Quorum-Sensing Histidine Protein Kinase of Streptococcus mutans.
abstract: Quorum sensing activation by signal pheromone (CSP) in Streptococcus mutans depends on the membrane-associated receptor ComD, which senses the signal and triggers the signaling cascade for bacteriocin production and other cell density-dependent activities. However, the mechanism of the signal recognition via the ComD receptor in this species is nearly unexplored. Here, we show that the membrane domain of the ComD protein forms six transmembrane segments with three extracellular loops, loopA, loopB and loopC. By structural and functional analyses of these extracellular loops, we demonstrate that both loopC and loopB are required for CSP recognition, while loopA plays little role in CSP detection. A deletion or substitution mutation of four residues NVIP in loopC abolishes CSP recognition for quorum sensing activities. We conclude that both loopC and loopB are required for forming the receptor and residues NVIP of loopC are essential for CSP recognition and quorum sensing activation in S. mutans.
authors.affiliation: Department of Applied Oral Sciences 5981 University Ave, Halifax, NS, B3H 1W2, Canada.
authors.forename: Gaofeng
authors.initials: G
authors.lastname: Dong
authors.affiliation: Department of Applied Oral Sciences 5981 University Ave, Halifax, NS, B3H 1W2, Canada.
authors.forename: Xiao-Lin
authors.initials: XL
authors.lastname: Tian
authors.affiliation: Department of Applied Oral Sciences 5981 University Ave, Halifax, NS, B3H 1W2, Canada.
authors.forename: Kayla
authors.initials: K
authors.lastname: Cyr
authors.affiliation: Department of Applied Oral Sciences 5981 University Ave, Halifax, NS, B3H 1W2, Canada.
authors.forename: Tianlei
authors.initials: T
authors.lastname: Liu
authors.affiliation: Department of Microbiology and Immunology, 5850 College Street, Halifax, NS, B3H 4R2, Canada.
authors.forename: William
authors.initials: W
authors.lastname: Lin
authors.affiliation: Department of Microbiology and Immunology, 5850 College Street, Halifax, NS, B3H 4R2, Canada.
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Tziolas
authors.affiliation: Department of Applied Oral Sciences 5981 University Ave, Halifax, NS, B3H 1W2, Canada.|Department of Microbiology and Immunology, 5850 College Street, Halifax, NS, B3H 4R2, Canada.
authors.forename: Yung-Hua
authors.initials: YH
authors.lastname: Li
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D000071677:Histidine Kinase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017354:Point Mutation; D011487:Protein Conformation; D053038:Quorum Sensing; D013295:Streptococcus mutans / Q000378:metabolism / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D000071677:Histidine Kinase