title: Salmonella acquires lysosome-associated membrane protein 1 (LAMP1) on phagosomes from Golgi via SipC protein-mediated recruitment of host Syntaxin6.
abstract: Several intracellular pathogens have developed diverse strategies to avoid targeting to lysosomes. However, they universally recruit lysosome-associated membrane protein 1 (LAMP1); the mechanism of LAMP1 recruitment remains unclear. Here, we report that a Salmonella effector protein, SipC, specifically binds with host Syntaxin6 through its C terminus and thereby recruits Syntaxin6 and other accessory molecules like VAMP2, Rab6, and Rab8 on Salmonella-containing phagosomes (SCP) and acquires LAMP1 by fusing with LAMP1-containing Golgi-derived vesicles. In contrast, sipC knock-out:SCP (sipC(-):SCP) or sipC(M398K):SCP fails to obtain significant amounts of Syntaxin6 and is unable to acquire LAMP1. Moreover, phagosomes containing respective knock-out Salmonella like sipA(-), sipB(-), sipD(-), sopB(-), or sopE(-) recruit LAMP1, demonstrating the specificity of SipC in this process. In addition, depletion of Syntaxin6 by shRNA in macrophages significantly inhibits LAMP1 recruitment on SCP. Additionally, survival of sipC(-):Salmonella in mice is found to be significantly inhibited in comparison with WT:Salmonella. Our results reveal a novel mechanism showing how Salmonella acquires LAMP1 through a SipC-Syntaxin6-mediated interaction probably to stabilize their niche in macrophages and also suggest that similar modalities might be used by other intracellular pathogens to recruit LAMP1.
authors.affiliation: National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067, India.
authors.forename: Richa
authors.initials: R
authors.lastname: Madan
authors.forename: Ruchir
authors.initials: R
authors.lastname: Rastogi
authors.forename: Seetharaman
authors.initials: S
authors.lastname: Parashuraman
authors.forename: Amitabha
authors.initials: A
authors.lastname: Mukhopadhyay
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D006056:Golgi Apparatus / Q000378:metabolism* / Q000382:microbiology; D042541:Intracellular Space / Q000378:metabolism / Q000382:microbiology; D052118:Lysosomal-Associated Membrane Protein 1 / Q000378:metabolism*; D008264:Macrophages / Q000166:cytology / Q000378:metabolism / Q000382:microbiology; D051379:Mice; D009154:Mutation; D010588:Phagosomes / Q000378:metabolism* / Q000382:microbiology*; D021381:Protein Transport; D050765:Qa-SNARE Proteins / Q000378:metabolism*; D012486:Salmonella typhimurium / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D052118:Lysosomal-Associated Membrane Protein 1; D050765:Qa-SNARE Proteins; C094578:Salmonella invasion protein C