SopB-Mediated Recruitment of SNX18 Facilitates Salmonella Typhimurium Internalization by the Host Cell. 2017

David Liebl, and Xiaying Qi, and Yang Zhe, and Timothy C Barnett, and Rohan D Teasdale
Institute for Molecular Bioscience, The University of QueenslandBrisbane, QLD, Australia.

To invade epithelial cells, Salmonella enterica serovar Typhimurium (S. Typhimurium) induces macropinocytosis through the action of virulence proteins delivered across the host cell membrane via a type III secretion system. We show that after docking at the plasma membrane S. Typhimurium triggers rapid recruitment of cytosolic SNX18, a SH3-PX-BAR domain sorting nexin protein, to the bacteria-induced membrane ruffles and to the nascent Salmonella-containing vacuole. SNX18 recruitment required the inositol-phosphatase activity of the Salmonella effector SopB and an intact phosphoinositide-binding site within the PX domain of SNX18, but occurred independently of Rho-GTPases Rac1 and Cdc42 activation. SNX18 promotes formation of the SCV from the plasma membrane by acting as a scaffold to recruit Dynamin-2 and N-WASP in a process dependent on the SH3 domain of SNX18. Quantification of bacteria uptake revealed that overexpression of SNX18 increased bacteria internalization, whereas a decrease was detected in cells overexpressing the phosphoinositide-binding mutant R303Q, the ΔSH3 mutant, and in cells where endogenous levels of SNX18 were knocked-down. This study identifies SNX18 as a novel target of SopB and suggests a mechanism where S. Typhimurium engages host factors via local manipulation of phosphoinositide composition at the site of invasion to orchestrate the internalization process.

UI MeSH Term Description Entries
D009154 Mutation Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations. Mutations
D010716 Phosphatidylinositols Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to the hexahydroxy alcohol, myo-inositol. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid, myo-inositol, and 2 moles of fatty acids. Inositide Phospholipid,Inositol Phosphoglyceride,Inositol Phosphoglycerides,Inositol Phospholipid,Phosphoinositide,Phosphoinositides,PtdIns,Inositide Phospholipids,Inositol Phospholipids,Phosphatidyl Inositol,Phosphatidylinositol,Inositol, Phosphatidyl,Phosphoglyceride, Inositol,Phosphoglycerides, Inositol,Phospholipid, Inositide,Phospholipid, Inositol,Phospholipids, Inositide,Phospholipids, Inositol
D010744 Phosphoric Monoester Hydrolases A group of hydrolases which catalyze the hydrolysis of monophosphoric esters with the production of one mole of orthophosphate. Phosphatase,Phosphatases,Phosphohydrolase,Phosphohydrolases,Phosphomonoesterase,Phosphomonoesterases,Phosphoric Monoester Hydrolase,Hydrolase, Phosphoric Monoester,Hydrolases, Phosphoric Monoester,Monoester Hydrolase, Phosphoric
D010873 Pinocytosis The engulfing of liquids by cells by a process of invagination and closure of the cell membrane to form fluid-filled vacuoles. Pinocytoses
D011810 Quinoxalines Quinoxaline
D002462 Cell Membrane The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells. Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D003600 Cytosol Intracellular fluid from the cytoplasm after removal of ORGANELLES and other insoluble cytoplasmic components. Cytosols
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000067996 RAW 264.7 Cells A transformed macrophage cell line isolated from ASCITES of mice infected with ABELSON MURINE LEUKEMIA VIRUS. RAW 264.7 Cell Line,264.7 Cell, RAW,264.7 Cells, RAW,Cell, RAW 264.7,Cells, RAW 264.7,RAW 264.7 Cell
D000069296 Type III Secretion Systems Multiprotein transmembrane complexes in GRAM-NEGATIVE BACTERIA involved in either the secretion of effector proteins from the bacterial cytoplasm into host cells, or the secretion and assembly of flagellar components. The major component of the T3SSs is called the injectosome or needle complex. Bacterial Secretion System, Type III,T3SS Secretion System,Type 3 Secretion System,Type 3 Secretion Systems,Type III Secretion System,Secretion System, T3SS,System, T3SS Secretion

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