Dataset Information

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.

SUBMITTER: Madan R

PROVIDER: S-EPMC3285332 | biostudies-literature | 2012 Feb

REPOSITORIES: biostudies-literature

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Salmonella acquires lysosome-associated membrane protein 1 (LAMP1) on phagosomes from Golgi via SipC protein-mediated recruitment of host Syntaxin6.

Madan Richa R Rastogi Ruchir R Parashuraman Seetharaman S Mukhopadhyay Amitabha A

The Journal of biological chemistry 20111221 8

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 LAMP ...[more]

PMID: 22190682

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Project description:Intracellular pathogens such as Salmonella depend on their molecular virulence factors to evade host defense responses like autophagy. Using a zebrafish systemic infection model, we have previously shown that phagocytes, predominantly macrophages, target Salmonella Typhimurium by an autophagy-related pathway known as Lc3-associated phagocytosis (LAP), which is dependent on the host protein Rubicon. Here, we explore the influence of Salmonella virulence factors on pathogenicity in the zebrafish model and induction of LAP as a defense response. We investigated five mutant strains that all could trigger GFP-Lc3 recruitment as puncta or rings around single bacteria or bacterial clusters, in a Rubicon-dependent manner. We found that S. Typhimurium strains carrying mutations in PhoP or PurA, responsible for adaptation to the intracellular environment and efficient metabolism of purines, respectively, are attenuated in the zebrafish model. However, both strains show increased virulence when LAP is inhibited by knockdown of Rubicon. Mutations in type III secretion systems 1 and 2, SipB and SsrB, which are important for invading and replicating in non-phagocytic cells, did not affect the ability to establish successful infection in the zebrafish model. This observation is in line with our previous characterization of this infection model revealing that macrophages actively phagocytose the majority of S. Typhimurium. In contrast to SipB mutants, SsrB mutants were unable to become more virulent in Rubicon-deficient hosts, suggesting that type III system 2 effectors are important for intracellular replication of Salmonella in the absence of LAP. Finally, we found that mutation of FlhD, required for production of flagella, renders S. Typhimurium hypervirulent both in wild type zebrafish embryos and in Rubicon-deficient hosts. FlhD mutation also led to lower levels of GFP-Lc3 recruitment compared with the wild type strain, indicating that recognition of flagellin by the host innate immune system promotes the LAP response. Together, our results provide new evidence that the Rubicon-dependent LAP process is an important defense mechanism against S. Typhimurium.

Dataset Information

Salmonella acquires lysosome-associated membrane protein 1 (LAMP1) on phagosomes from Golgi via SipC protein-mediated recruitment of host Syntaxin6.

Publications

Salmonella acquires lysosome-associated membrane protein 1 (LAMP1) on phagosomes from Golgi via SipC protein-mediated recruitment of host Syntaxin6.

Similar Datasets

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