Identification of a<i>Francisella tularensis</i>LVS outer membrane protein that confers adherence to A549 human lung cells

Melillo, Amanda A.; Sledjeski, Darren D.; Lipski, Serena; Wooten, R. Mark; Basrur, Venkatesha; Lafontaine, Eric R.

doi:10.1111/j.1574-6968.2006.00413.x

Cited by 50 publications

(59 citation statements)

References 24 publications

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“…In V. cholerae, the BcsL B and BcsK C homologs VipA and VipB have been described as nonsecreted cytosolic proteins (32). In F. novicida, the BcsL B and BcsK C homologs IglA and IglB have been described as strictly cytosolic proteins (11) or as surface-exposed proteins (49,50). In E. tarda, EvpA (BcsL B ) interacts with the periplasmic domain of IcmF (12), suggesting that BcsL B homologs might have a periplasmic location.…”

Section: Discussionmentioning

confidence: 99%

BcsKC Is an Essential Protein for the Type VI Secretion System Activity in Burkholderia cenocepacia That Forms an Outer Membrane Complex with BcsLB

Aubert

MacDonald

Valvano

2010

Journal of Biological Chemistry

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The type VI secretion system (T6SS) contributes to the virulence of Burkholderia cenocepacia, an opportunistic pathogen causing serious chronic infections in patients with cystic fibrosis. BcsK C is a highly conserved protein among the T6SSs in Gram-negative bacteria. Here, we show that BcsK C is required for Hcp secretion and cytoskeletal redistribution in macrophages upon bacterial infection. These two phenotypes are associated with a functional T6SS in B. cenocepacia. Experiments employing a bacterial two-hybrid system and pulldown assays demonstrated that BcsK C interacts with BcsL B , another conserved T6SS component. Internal deletions within BcsK C revealed that its N-terminal domain is necessary and sufficient for interaction with BcsL B . Fractionation experiments showed that BcsK C can be in the cytosol or tightly associated with the outer membrane and that BcsK C and BcsL B form a high molecular weight complex anchored to the outer membrane that requires BcsF H (a ClpV homolog) to be assembled. Together, our data show that BcsK C /BcsL B interaction is essential for the T6SS activity in B. cenocepacia.

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Section: Discussionmentioning

confidence: 99%

BcsKC Is an Essential Protein for the Type VI Secretion System Activity in Burkholderia cenocepacia That Forms an Outer Membrane Complex with BcsLB

Aubert

MacDonald

Valvano

2010

Journal of Biological Chemistry

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“…It is established that Francisella bacteria replicate in the cytosol of primary macrophages and macrophagelike cell lines (18,56,66), and recent data indicate that these organisms also parasitize primary alveolar epithelial cells and epithelial cell lines (21,35,46,57,61). In this regard, it is noteworthy that disruption of pyrB in SchuS4 slows bacterial growth in HepG2 epithelial cells (63).…”

Section: Identification Of Lvs Tn5 Mutants That No Longer Prevent Neumentioning

confidence: 99%

Francisella tularensisGenes Required for Inhibition of the Neutrophil Respiratory Burst and Intramacrophage Growth Identified by Random Transposon Mutagenesis of Strain LVS

Schulert

McCaffrey

Buchan³

et al. 2009

Infect Immun

111

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Francisella tularensis is a facultative intracellular pathogen and the causative agent of tularemia. We have shown that F. tularensis subspecies holarctica strain LVS prevents NADPH oxidase assembly and activation in human neutrophils, but how this is achieved is unclear. Herein, we used random transposon mutagenesis to identify LVS genes that affect neutrophil activation. Our initial screen identified carA, carB, and pyrB, which encode the small and large subunits of carbamoylphosphate synthase and aspartate carbamoyl transferase, respectively. These strains are uracil auxotrophs, and their growth was attenuated on cysteine heart agar augmented with sheep blood (CHAB) or in modified Mueller-Hinton broth. Phagocytosis of the uracil auxotrophic mutants triggered a respiratory burst in neutrophils, and ingested bacteria were killed and fragmented in phagosomes that contained superoxide. Conversely, phagocytosis did not trigger a respiratory burst in blood monocytes or monocyte-derived macrophages (MDM), and phagosomes containing wild-type or mutant bacteria lacked NADPH oxidase subunits. Nevertheless, the viability of mutant bacteria declined in MDM, and ultrastructural analysis revealed that phagosome egress was significantly inhibited despite synthesis of the virulence factor IglC. Other aspects of infection, such as interleukin-1␤ (IL-1␤) and IL-8 secretion, were unaffected. The cultivation of carA, carB, or pyrB on uracil-supplemented CHAB was sufficient to prevent neutrophil activation and intramacrophage killing and supported escape from MDM phagosomes, but intracellular growth was not restored unless uracil was added to the tissue culture medium. Finally, all mutants tested grew normally in both HepG2 and J774A.1 cells. Collectively, our data demonstrate that uracil auxotrophy has cell type-specific effects on the fate of Francisella bacteria.

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“…Each of these MAbs recognizes a different protein antigen, and each of these antigens is a target for the murine or human antibody response to F. tularensis, suggesting that these antigens could contribute to the development of a subunit vaccine. Several groups have recently demonstrated that FopA (27,28,37), LpnA (27,37), DnaK (27,28,37), SucB (28,37,40), Bfr (37,40), and RplL (28) are components of the bacterial membrane. All six of these antigens were identified as reactive with serum from human tularemia patients (28) and five of them (all except Bfr) with murine serum (57).…”

Section: Following Recovery From Sublethal Infection Boosting With Hmentioning

confidence: 99%

Francisella tularensisInfection-Derived Monoclonal Antibodies Provide Detection, Protection, and Therapy

Savitt

Mena-Taboada

Monsalve

et al. 2009

Clin Vaccine Immunol

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Francisella tularensis is the causative agent of tularemia and a potential agent of biowarfare. As an easily transmissible infectious agent, rapid detection and treatment are necessary to provide a positive clinical outcome. As an agent of biowarfare, there is an additional need to prevent infection. We made monoclonal antibodies to the F. tularensis subsp. holarctica live vaccine strain (F. tularensis LVS) by infecting mice with a sublethal dose of bacteria and, following recovery, by boosting the mice with sonicated organisms. The response to the initial and primary infection was restricted to immunoglobulin M antibody directed solely against lipopolysaccharide (LPS). After boosting with sonicated organisms, the specificity repertoire broadened against protein antigens, including DnaK, LpnA, FopA, bacterioferritin, the 50S ribosomal protein L7/L12, and metabolic enzymes. These monoclonal antibodies detect F. tularensis LVS by routine immunoassays, including enzyme-linked immunosorbent assay, Western blot analysis, and immunofluorescence. The ability of the antibodies to protect mice from intradermal infection, both prophylactically and therapeutically, was examined. An antibody to LPS which provides complete protection from infection with F. tularensis LVS and partial protection from infection with F. tularensis subsp. tularensis strain SchuS4 was identified. There was no bacteremia and reduced organ burden within the first 24 h when mice were protected from F. tularensis LVS infection with the anti-LPS antibody. No antibody that provided complete protection when administered therapeutically was identified; however, passive transfer of antibodies against LPS, FopA, and LpnA resulted in 40 to 50% survival of mice infected with F. tularensis LVS.

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Identification of aFrancisella tularensisLVS outer membrane protein that confers adherence to A549 human lung cells

Cited by 50 publications

References 24 publications

BcsKC Is an Essential Protein for the Type VI Secretion System Activity in Burkholderia cenocepacia That Forms an Outer Membrane Complex with BcsLB

BcsKC Is an Essential Protein for the Type VI Secretion System Activity in Burkholderia cenocepacia That Forms an Outer Membrane Complex with BcsLB

Francisella tularensisGenes Required for Inhibition of the Neutrophil Respiratory Burst and Intramacrophage Growth Identified by Random Transposon Mutagenesis of Strain LVS

Francisella tularensisInfection-Derived Monoclonal Antibodies Provide Detection, Protection, and Therapy

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