title: Bacillus bombysepticus α-Toxin Binding to G Protein-Coupled Receptor Kinase 2 Regulates cAMP/PKA Signaling Pathway to Induce Host Death.
abstract: Bacterial pathogens and their toxins target host receptors, leading to aberrant behavior or host death by changing signaling events through subversion of host intracellular cAMP level. This is an efficient and widespread mechanism of microbial pathogenesis. Previous studies describe toxins that increase cAMP in host cells, resulting in death through G protein-coupled receptor (GPCR) signaling pathways by influencing adenylyl cyclase or G protein activity. G protein-coupled receptor kinase 2 (GRK2) has a central role in regulation of GPCR desensitization. However, little information is available about the pathogenic mechanisms of toxins associated with GRK2. Here, we reported a new bacterial toxin-Bacillus bombysepticus (Bb) α-toxin that was lethal to host. We showed that Bb α-toxin interacted with BmGRK2. The data demonstrated that Bb α-toxin directly bound to BmGRK2 to promote death by affecting GPCR signaling pathways. This mechanism involved stimulation of Gαs, increase level of cAMP and activation of protein kinase A (PKA). Activated cAMP/PKA signal transduction altered downstream effectors that affected homeostasis and fundamental biological processes, disturbing the structural and functional integrity of cells, resulting in death. Preventing cAMP/PKA signaling transduction by inhibitions (NF449 or H-89) substantially reduced the pathogenicity of Bb α-toxin. The discovery of a toxin-induced host death specifically linked to GRK2 mediated signaling pathway suggested a new model for bacterial toxin action. Characterization of host genes whose expression and function are regulated by Bb α-toxin and GRK2 will offer a deeper understanding of the pathogenesis of infectious diseases caused by pathogens that elevate cAMP.
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, P. R. China.
authors.forename: Ping
authors.initials: P
authors.lastname: Lin
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, P. R. China.
authors.forename: Tingcai
authors.initials: T
authors.lastname: Cheng
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, P. R. China.
authors.forename: Sanyuan
authors.initials: S
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, P. R. China.
authors.forename: Junping
authors.initials: J
authors.lastname: Gao
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, P. R. China.
authors.forename: Shengkai
authors.initials: S
authors.lastname: Jin
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, P. R. China.
authors.forename: Liang
authors.initials: L
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, P. R. China.
authors.forename: Qingyou
authors.initials: Q
authors.lastname: Xia
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001407:Bacillus / Q000378:metabolism* / Q000472:pathogenicity; D001427:Bacterial Toxins / Q000378:metabolism*; D012831:Bombyx; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D054768:G-Protein-Coupled Receptor Kinases / Q000378:metabolism*; D006801:Humans; D007546:Isoquinolines / Q000494:pharmacology; D008954:Models, Biological; D015398:Signal Transduction; D013449:Sulfonamides / Q000494:pharmacology
chemical_list: D001427:Bacterial Toxins; D007546:Isoquinolines; D013449:Sulfonamides; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D054768:G-Protein-Coupled Receptor Kinases; D000262:Adenylyl Cyclases; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide