1. Proteomics of intracellular Salmonella enterica reveals roles of Salmonella pathogenicity island 2 in metabolism and antioxidant defense
- Author
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Tzu-Chiao Chao, Tatjana Reuter, Janina Noster, Nicole Hansmeier, Nathalie Sander, Michael Hensel, and Marc Schulte
- Subjects
Proteomics ,Salmonella ,Proteome ,Proteomes ,Centrifugation ,medicine.disease_cause ,Pathology and Laboratory Medicine ,Biochemistry ,Antioxidants ,Type three secretion system ,White Blood Cells ,Mice ,Animal Cells ,Medicine and Health Sciences ,Protein Interaction Maps ,Biology (General) ,Cells, Cultured ,Protein Metabolism ,0303 health sciences ,biology ,Chemistry ,Effector ,030302 biochemistry & molecular biology ,Cell biology ,Mutant Strains ,Separation Processes ,Intracellular Pathogens ,Salmonella enterica ,Cellular Types ,Pathogens ,Intracellular ,Research Article ,Genomic Islands ,QH301-705.5 ,Immune Cells ,Immunology ,Research and Analysis Methods ,Microbiology ,03 medical and health sciences ,Bacterial Proteins ,Virology ,medicine ,Genetics ,Animals ,Typhoid Fever ,Molecular Biology ,030304 developmental biology ,Blood Cells ,Intracellular parasite ,Macrophages ,Host Cells ,Biology and Life Sciences ,Proteins ,Computational Biology ,Cell Biology ,RC581-607 ,Salmonella typhi ,biology.organism_classification ,Pathogenicity island ,Metabolism ,Mutation ,Parasitology ,Immunologic diseases. Allergy ,Viral Transmission and Infection - Abstract
Intracellular Salmonella enterica serovar Typhimurium (STM) deploy the Salmonella Pathogenicity Island 2-encoded type III secretion system (SPI2-T3SS) for the massive remodeling of the endosomal system for host cells. This activity results in formation of an extensive interconnected tubular network of Salmonella-induced filaments (SIFs) connected to the Salmonella-containing vacuole (SCV). Such network is absent in cells infected with SPI2-T3SS-deficient mutant strains such as ΔssaV. A tubular network with reduced dimensions is formed if SPI2-T3SS effector protein SseF is absent. Previous single cell live microscopy-based analyses revealed that intracellular proliferation of STM is directly correlated to the ability to transform the host cell endosomal system into a complex tubular network. This network may also abrogate host defense mechanisms such as delivery of antimicrobial effectors to the SCV. To test the role of SIFs in STM patho-metabolism, we performed quantitative comparative proteomics of STM recovered from infected murine macrophages. We infected RAW264.7 cells with STM wild type (WT), ΔsseF or ΔssaV strains, recovered bacteria 12 h after infection and determined proteome compositions. Increased numbers of proteins characteristic for nutritional starvation were detected in STM ΔsseF and ΔssaV compared to WT. In addition, STM ΔssaV, but not ΔsseF showed signatures of increased exposure to stress by antimicrobial defenses, in particular reactive oxygen species, of the host cells. The proteomics analyses presented here support and extend the role of SIFs for the intracellular lifestyle of STM. We conclude that efficient manipulation of the host cell endosomal system by effector proteins of the SPI2-T3SS contributes to nutrition, as well as to resistance against antimicrobial host defense mechanisms., Author summary The facultative intracellular bacterium Salmonella enterica has evolved sophisticated mechanisms to adapt to life inside a pathogen-containing vacuole in mammalian host cells. Intracellular Salmonella manipulate the host cell endosomal system resulting in formation of a complex network of tubular vesicles, termed Salmonella-induced filaments (SIFs). We applied quantitative proteomics to intracellular Salmonella in murine macrophages and compared the wild-type strain to mutant strains with aberrant SIF architecture, or no capacity for induction of SIF. We determined that those mutant strains contain higher amounts of transporters for nutrient uptake, and lower amounts of proteins for central carbon metabolism. These observations indicate response to nutrient restriction in absence of fully established SIF. In addition, the mutant strain unable to induce SIF formation showed increased amounts of proteins required for response to antimicrobial factors of the host cells. These data show that the massive remodeling of the endosomal system of host cells by intracellular Salmonella serves to essential needs, i.e. to enable access to nutrients for efficient proliferation of the pathogen, and to withstand hostile conditions within the pathogen-containing vacuole.
- Published
- 2019