The COPII complex and lysosomal VAMP7 determine intracellularSalmonellalocalization and growth

Abstract

Salmonella invades epithelial cells and survives within a membrane-bound compartment, the Salmonella-containing vacuole (SCV). We isolated and determined the host protein composition of the SCV at 30 min and 3 h of infection to identify and characterize novel regulators of intracellular bacterial localization and growth. Quantitation of the SCV protein content revealed 392 host proteins specifically enriched at SCVs, out of which 173 associated exclusively with early SCVs, 124 with maturing SCV and 95 proteins during both time-points. Vacuole interactions with endoplasmic reticulum-derived coat protein complex II vesicles modulate early steps of SCV maturation, promoting SCV rupture and bacterial hyper-replication within the host cytosol. On the other hand, SCV interactions with VAMP7-positive lysosome-like vesicles promote Salmonella-induced filament formation and bacterial growth within the late SCV. Our results reveal that the dynamic communication between the SCV and distinct host organelles affects both intracellular Salmonella localization and growth at successive steps of host cell invasion.

COPII-dependent ER export in animal cells: adaptation and control for diverse cargo

“…It also facilitates the life cycles of some key pathogens including Salmonella (Santos et al 2015), Listeria (Gianfelice et al 2015), enteropathogenic E. coli , and Citrobacter (Thanabalasuriar et al 2013). Mutations in some COPII genes are implicated in osteogenesis imperfecta and related disorders (Garbes et al 2015), as well as other diseases including cancer (Lee et al 2016; Yehia et al 2015).…”

What the SIF Is Happening—The Role of Intracellular Salmonella-Induced Filaments

“…These included: VCP (a transitional endoplasmic reticulum ATPase), ER localized GTPases (Rab2, Rab10, Sar1A), and vesicle coat proteins associated with coatomer protein complexes I and II (COPI and COPII, respectively). Another group demonstrated that the early SCV physically interacts with the ER via ER filaments wrapped around the SCV (Santos et al, 2015). This ER-SCV interaction was observed using high-resolution ultrastructural imaging combined with immunofluorescence to give higher resolution than light or confocal microscopy alone (Narayan and Subramaniam, 2015; Santos et al, 2015).…”

“…Another group demonstrated that the early SCV physically interacts with the ER via ER filaments wrapped around the SCV (Santos et al, 2015). This ER-SCV interaction was observed using high-resolution ultrastructural imaging combined with immunofluorescence to give higher resolution than light or confocal microscopy alone (Narayan and Subramaniam, 2015; Santos et al, 2015). Santos et al (2015) also showed via proteomics that COPII complexes accumulate on the early SCV membrane.…”

“…Like Salmonella, Legionella and M. tuberculosis largely remain and replicate within a BCV, while Shigella, Francisella , and Edwardsiella escape their vacuoles and replicate within the host cell's cytoplasm (Okuda et al, 2006; Santos and Enninga, 2016). This review focuses on intravacuolar Salmonella , but a small portion of Salmonella (around 10%) escape the SCV and enter a hyper-replicative state within the cytosol of epithelial cells (Knodler et al, 2010; Malik-Kale et al, 2012; Yu et al, 2014; Santos et al, 2015). …”

Omics in Aid of Host-pathogen Interaction Studies: A Bacterial Perspective

“…By means of subcellular fractionation of infected cells using sucrose-density centrifugation, SCVs can be fairly purely isolated with subsequent recovery of viable bacteria. In the work of Santos et al [63], the authors report a recovery of about 30 million bacterial cells when infecting 60 million HeLa cells at a MOI of 100. Inclusion of an immunopreciptitation (IP) step, such as the SseF IP performed in [64] and targeting a Salmonella secreted effector residing in the SCV membrane, might also be considered as a bacterial enrichment method as it yields purer SCV fractions.…”