title: A Salmonella typhimurium-translocated glycerophospholipid:cholesterol acyltransferase promotes virulence by binding to the RhoA protein switch regions.
abstract: Salmonella enterica serovar typhimurium translocates a glycerophospholipid:cholesterol acyltransferase (SseJ) into the host cytosol after its entry into mammalian cells. SseJ is recruited to the cytoplasmic face of the host cell phagosome membrane where it is activated upon binding the small GTPase, RhoA. SseJ is regulated similarly to cognate eukaryotic effectors, as only the GTP-bound form of RhoA family members stimulates enzymatic activity. Using NMR and biochemistry, this work demonstrates that SseJ competes effectively with Rhotekin, ROCK, and PKN1 in binding to a similar RhoA surface. The RhoA surface that binds SseJ includes the regulatory switch regions that control activation of mammalian effectors. These data were used to create RhoA mutants with altered SseJ binding and activation. This structure-function analysis supports a model in which SseJ activation occurs predominantly through binding to residues within switch region II. We further defined the nature of the interaction between SseJ and RhoA by constructing SseJ mutants in the RhoA binding surface. These data indicate that SseJ binding to RhoA is required for recruitment of SseJ to the endosomal network and for full Salmonella virulence for inbred susceptible mice, indicating that regulation of SseJ by small GTPases is an important virulence strategy of this bacterial pathogen. The dependence of a bacterial effector on regulation by a mammalian GTPase defines further how intimately host pathogen interactions have coevolved through similar and divergent evolutionary strategies.
authors: Department of Microbiology, University of Washington, Seattle, WA 98195, USA.
authors: Doris L
authors: DL
authors: LaRock
authors: Peter S
authors: PS
authors: Brzovic
authors: Itay
authors: I
authors: Levin
authors: Marie-Pierre
authors: MP
authors: Blanc
authors: Samuel I
authors: SI
authors: Miller
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D051017:Apoptosis Regulatory Proteins; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D009154:Mutation; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012480:Salmonella Infections / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D012486:Salmonella typhimurium / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D013329:Structure-Activity Relationship; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: D051017:Apoptosis Regulatory Proteins; D001426:Bacterial Proteins; D047908:Intracellular Signaling Peptides and Proteins; C100494:RTKN protein, human; C498395:Rtkn protein, mouse; D037521:Virulence Factors; C066737:RHOA protein, human; D000217:Acyltransferases; C020597:glycerophospholipid-cholesterol acyltransferase; C061570:protein kinase N; D011493:Protein Kinase C; D019204:GTP-Binding Proteins; C526380:RhoA protein, mouse; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein