[PDF][PDF] A bacterial pathogen targets a host Rab-family GTPase defense pathway with a GAP

S Spanò, X Gao, S Hannemann, M Lara-Tejero… - Cell host & …, 2016 - cell.com
Cell host & microbe, 2016cell.com
Cell-autonomous defense mechanisms are potent strategies that protect individual cells
against intracellular pathogens. The Rab-family GTPase Rab32 was previously shown to
restrict the intracellular human pathogen Salmonella Typhi, but its potential broader role in
antimicrobial defense remains unknown. We show that Rab32 represents a general cell-
autonomous, antimicrobial defense that is counteracted by two Salmonella effectors. Mice
lacking Rab-32 or its nucleotide exchange factor BLOC-3 are permissive to S. Typhi …
Summary
Cell-autonomous defense mechanisms are potent strategies that protect individual cells against intracellular pathogens. The Rab-family GTPase Rab32 was previously shown to restrict the intracellular human pathogen Salmonella Typhi, but its potential broader role in antimicrobial defense remains unknown. We show that Rab32 represents a general cell-autonomous, antimicrobial defense that is counteracted by two Salmonella effectors. Mice lacking Rab-32 or its nucleotide exchange factor BLOC-3 are permissive to S. Typhi infection and exhibit increased susceptibility to S. Typhimurium. S. Typhimurium counters this defense pathway by delivering two type III secretion effectors, SopD2, a Rab32 GAP, and GtgE, a specific Rab32 protease. An S. Typhimurium mutant strain lacking these two effectors exhibits markedly reduced virulence, which is fully restored in BLOC-3-deficient mice. These results demonstrate that a cell-autonomous, Rab32-dependent host defense pathway plays a central role in the defense against vacuolar pathogens and describe a mechanism evolved by a bacterial pathogen to counter it.
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