Role of host cell-derived amino acids in nutrition of intracellular Salmonella enterica.
The facultative intracellular pathogen Salmonella enterica resides in a specific membrane-bound compartment termed the Salmonella-containing vacuole (SCV). Despite being segregated from access to metabolites in the host cell cytosol, Salmonella is able to efficiently proliferate within the SCV. We set out to unravel the nutritional supply of Salmonella in the SCV with focus on amino acids. We studied the availability of amino acids by the generation of auxotrophic strains for alanine, asparagine, aspartate, glutamine, and proline in a macrophage cell line (RAW264.7) and an epithelial cell line (HeLa) and examined access to extracellular nutrients for nutrition. Auxotrophies for alanine, asparagine, or proline attenuated intracellular replication in HeLa cells, while aspartate, asparagine, or proline auxotrophies attenuated intracellular replication in RAW264.7 macrophages. The different patterns of intracellular attenuation of alanine- or aspartate-auxotrophic strains support distinct nutritional conditions in HeLa cells and RAW264.7 macrophages. Supplementation of medium with individual amino acids restored the intracellular replication of mutant strains auxotrophic for asparagine, proline, or glutamine. Similarly, a mutant strain deficient in succinate dehydrogenase was complemented by the extracellular addition of succinate. Complementation of the intracellular replication of auxotrophic Salmonella by external amino acids was possible if bacteria were proficient in the induction of Salmonella-induced filaments (SIFs) but failed in a SIF-deficient background. We propose that the ability of intracellular Salmonella to redirect host cell vesicular transport provides access of amino acids to auxotrophic strains and, more generally, is essential to continuously supply bacteria within the SCV with nutrients.
Abteilung Mikrobiologie, Universität Osnabrück, Osnabrück, Germany.
Jasmin
J
Popp
Abteilung Mikrobiologie, Universität Osnabrück, Osnabrück, Germany.
Janina
J
Noster
Abteilung Mikrobiologie, Universität Osnabrück, Osnabrück, Germany.
Kim
K
Busch
Abteilung Mikrobiologie, Universität Osnabrück, Osnabrück, Germany.
Alexander
A
Kehl
Abteilung Mikrobiologie, Universität Osnabrück, Osnabrück, Germany.
Gero
G
Zur Hellen
Abteilung Mikrobiologie, Universität Osnabrück, Osnabrück, Germany Michael.Hensel@biologie.uni-osnabrueck.de.
Michael
M
Hensel
D000409:Alanine / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001216:Asparagine / Q000378:metabolism / Q000494:pharmacology; D001224:Aspartic Acid / Q000378:metabolism / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005973:Glutamine / Q000378:metabolism / Q000494:pharmacology; D006023:Glycoproteins / Q000235:genetics* / Q000378:metabolism; D006367:HeLa Cells; D054884:Host-Pathogen Interactions; D006801:Humans; D051379:Mice; D011392:Proline / Q000378:metabolism / Q000494:pharmacology; D019779:Salmonella enterica / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D013385:Succinate Dehydrogenase / Q000172:deficiency / Q000235:genetics; D019802:Succinic Acid / Q000378:metabolism / Q000494:pharmacology; D014617:Vacuoles / Q000187:drug effects / Q000378:metabolism* / Q000382:microbiology
D001426:Bacterial Proteins; D006023:Glycoproteins; C421862:SifA protein, Salmonella; D005973:Glutamine; D001224:Aspartic Acid; D001216:Asparagine; D011392:Proline; D019802:Succinic Acid; D013385:Succinate Dehydrogenase; D000409:Alanine