Salmonella – At Home in the Host Cell

Abstract

The Gram-negative bacterium Salmonella enterica has developed an array of sophisticated tools to manipulate the host cell and establish an intracellular niche, for successful propagation as a facultative intracellular pathogen. While Salmonella exerts diverse effects on its host cell, only the cell biology of the classic “trigger”-mediated invasion process and the subsequent development of the Salmonella-containing vacuole have been investigated extensively. These processes are dependent on cohorts of effector proteins translocated into host cells by two type III secretion systems (T3SS), although T3SS-independent mechanisms of entry may be important for invasion of certain host cell types. Recent studies into the intracellular lifestyle of Salmonella have provided new insights into the mechanisms used by this pathogen to modulate its intracellular environment. Here we discuss current knowledge of Salmonella-host interactions including invasion and establishment of an intracellular niche within the host.

Impact ofSalmonella entericaType III Secretion System Effectors on the Eukaryotic Host Cell

“…Additional hallmarks of the biogenesis of the SCV are the movement of the vacuole from the plasma membrane to a perinuclear position [42], the recruitment of several members of the Rab family of small GTPases [43], the interaction with endocytic and exocytic pathways, and the involvement of T3SS1 and T3SS2 effectors in the modulation of the process. The SCV biogenesis can be divided arbitrarily into three stages: early (10 min-1 h postinfection), intermediate (1 h-4 h), and late (>4 h) [8,41] ( Figure 4).…”

“…It translocates effectors across the membrane of the SCV. These effectors are required for the modulation of the intracellular environment [8].…”

Intracellular Salmonella induces aggrephagy of host endomembranes in persistent infections

“…2,10 S. enterica serovar Typhimurium (S. Typhimurium) is an intracellular bacterial pathogen that infects phagocytic and nonphagocytic eukaryotic cells and resides in a specialized phagosomal compartment named the SCV, for Salmonellacontaining vacuole. [11][12][13] In vivo, S. Typhimurium preferentially colonizes macrophages, both in target organs and in lymph nodes.…”

“…S. Typhimurium proliferation within epithelial cells associates to a profound reorganization of host endomembranes. 11 The pathogen subverts vesicular trafficking by targeting motor proteins such as dynein and kinesin, which leads to formation of tubules termed SIF, for Salmonella-induced filaments. 21 SIF are enriched in lysosomal membrane glycoproteins (LGP), emanate from the SCV and are proposed as the main source of membrane and nutrients for proliferation of intraphagosomal bacteria.…”

Application of Fluorescent Nanoparticles to Study Remodeling of the Endo-lysosomal System by Intracellular Bacteria

“…After being internalized, the pathogens, either localized in the cytosol or sequestered in membrane-bound compartments, interact extensively with their host environments and modulate these to favor their own survival 10 . For instance, Salmonella enterica resides and replicates within an intracellular phagosomal compartment termed the Salmonella-containing vacuole (SCV) upon infection 11 . The maturing SCV traffics towards the Golgi apparatus, undergoing continuous interactions with the endocytic pathway, and induces formation of extensive tubular structures, such as Salmonella-induced filaments (SIF), sorting nexin tubules, Salmonella-induced secretory carrier membrane protein 3 (SCAMP3) tubules, etc.…”