title: Effects of lysosomal membrane protein depletion on the Salmonella-containing vacuole.
abstract: Salmonella is an intracellular bacterial pathogen that replicates within a membrane-bound vacuole in host cells. The major lysosomal membrane proteins 1 and 2 (LAMP-1 and LAMP-2) are recruited to the Salmonella-containing vacuole as well as Salmonella- associated filaments (Sifs) that emerge from the vacuole. LAMP-1 is a dominant membrane marker for the vacuole and Sifs. Its colocalization with both is dependent on a major secreted bacterial virulence protein, SifA. Here, we show that SifA is required for the recruitment of LAMP-2 and can be used as a second independent marker for both the bacterial vacuolar membrane and Sifs. Further, RNAi studies revealed that in LAMP-1 depleted cells, the bacteria remain membrane bound as measured by their association with LAMP-2 protein. In contrast, LAMP-2 depletion increased the amount of LAMP-1 free bacteria. Together, the data suggests that despite its abundance, LAMP-1 is not essential, but LAMP-2 may be partially important for the Salmonella-containing vacuolar membrane.
authors.affiliation: Department of Microbiology-Immunology, Northwestern University, Chicago, Illinois, USA.
authors.forename: Everett A
authors.initials: EA
authors.lastname: Roark
authors.forename: Kasturi
authors.initials: K
authors.lastname: Haldar
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D001692:Biological Transport / Q000235:genetics; D049109:Cell Proliferation / Q000187:drug effects; D055785:Gene Knockdown Techniques; D006023:Glycoproteins / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D052119:Lysosomal-Associated Membrane Protein 2; D051907:Lysosomal Membrane Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology; D034741:RNA, Small Interfering / Q000494:pharmacology; D012480:Salmonella Infections / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D012486:Salmonella typhimurium / Q000235:genetics / Q000378:metabolism*; D014617:Vacuoles / Q000235:genetics / Q000378:metabolism / Q000382:microbiology*; D052118:Lysosomal-Associated Membrane Protein 1
chemical_list: D001426:Bacterial Proteins; D006023:Glycoproteins; D052119:Lysosomal-Associated Membrane Protein 2; D051907:Lysosomal Membrane Proteins; D034741:RNA, Small Interfering; C489116:LAMP1 protein, human; D052118:Lysosomal-Associated Membrane Protein 1; C497811:LAMP2 protein, human; C421862:SifA protein, Salmonella