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Salmonella type III effector SopB modulates host cell exocytosis.

Perrett CA, Zhou D - Emerg Microbes Infect (2013)

Bottom Line: Type III effectors interact with the host cell endocytic pathway to aid replication.We investigated whether Salmonella effector proteins may also interact with the host's exocytic pathway.The 4-phosphatase activity of SopB was crucial to its effect on exocytosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Purdue University , West Lafayette, IN 47907, USA.

ABSTRACT
Salmonella enterica pathogenesis is dependent on its ability to enter and replicate inside host cells. Replication occurs inside the Salmonella-containing vacuole (SCV), a vacuolar compartment that is modified by bacterial effectors secreted through the two type III secretion systems (T3SS-1 and T3SS-2). Type III effectors interact with the host cell endocytic pathway to aid replication. We investigated whether Salmonella effector proteins may also interact with the host's exocytic pathway. A secreted alkaline phosphatase (SEAP) assay indicated three Salmonella effectors inhibited the secretory pathway, although only Salmonella outer protein B (SopB) was confirmed to block exocytosis using a vesicular stomatitis virus glycoprotein-green fluorescent protein (VSVG-GFP) transport assay. The 4-phosphatase activity of SopB was crucial to its effect on exocytosis. The interaction with the secretory pathway could potentially be important for providing replicating Salmonella with nutrients, contributing membrane material necessary for SCV biogenesis, altering antibacterial peptide/protein secretion or manipulating cell surface proteins important in the host response to infection.

No MeSH data available.


Related in: MedlinePlus

SopB delays transport of VSVG between the ER and Golgi. Immunoblot analysis of VSVG in cells cotransfected with ts045VSVG-GFP and either pEGFP-N2 (control), pEGFP-N2-SopB (SopB) or pEGFP-N2-SopBc/s (SopBc/s) at various time points after the shift to 32 °C. Endoglycosidase H (Endo H)-treated (+) and mock-treated (−) samples are indicated. The mobility of the Endo H-resistant (R; upper band) and -sensitive (S; lower band) forms of the protein is indicated. The boxes in B and C indicate the different Endo H sensitivity pattern exhibited by SopB-transfected cells. Actin immunoblotting is included as a loading control.
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fig4: SopB delays transport of VSVG between the ER and Golgi. Immunoblot analysis of VSVG in cells cotransfected with ts045VSVG-GFP and either pEGFP-N2 (control), pEGFP-N2-SopB (SopB) or pEGFP-N2-SopBc/s (SopBc/s) at various time points after the shift to 32 °C. Endoglycosidase H (Endo H)-treated (+) and mock-treated (−) samples are indicated. The mobility of the Endo H-resistant (R; upper band) and -sensitive (S; lower band) forms of the protein is indicated. The boxes in B and C indicate the different Endo H sensitivity pattern exhibited by SopB-transfected cells. Actin immunoblotting is included as a loading control.

Mentions: To monitor the effect of SopB on VSVG trafficking, 293T cells were cotransfected with ts045-VSVG-GFP and either vector, SopB or SopBc/s. Cells were shifted to 40 °C overnight before cycloheximide was added to inhibit further protein synthesis and cells were shifted to 32 °C for various lengths of time to monitor VSVG transport. The vector- and SopBc/s-transfected cells exhibited similar behaviour, namely, that 1 h after the temperature shift the majority of the VSVG protein is Endo H-resistant and therefore has reached the Golgi (Figure 4). In contrast, cells transfected with SopB, show VSVG sensitivity to Endo H up to 2 h after the temperature shift, indicating that, in these cells, some of the VSVG protein remains localized to the ER (Figures 4B and 4C). Therefore, in the presence of SopB the transport of VSVG between the ER and Golgi is inhibited or delayed. The phosphatidylinositol phosphatase activity of SopB is important for this delay in transport between the ER and Golgi.


Salmonella type III effector SopB modulates host cell exocytosis.

Perrett CA, Zhou D - Emerg Microbes Infect (2013)

SopB delays transport of VSVG between the ER and Golgi. Immunoblot analysis of VSVG in cells cotransfected with ts045VSVG-GFP and either pEGFP-N2 (control), pEGFP-N2-SopB (SopB) or pEGFP-N2-SopBc/s (SopBc/s) at various time points after the shift to 32 °C. Endoglycosidase H (Endo H)-treated (+) and mock-treated (−) samples are indicated. The mobility of the Endo H-resistant (R; upper band) and -sensitive (S; lower band) forms of the protein is indicated. The boxes in B and C indicate the different Endo H sensitivity pattern exhibited by SopB-transfected cells. Actin immunoblotting is included as a loading control.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3675406&req=5

fig4: SopB delays transport of VSVG between the ER and Golgi. Immunoblot analysis of VSVG in cells cotransfected with ts045VSVG-GFP and either pEGFP-N2 (control), pEGFP-N2-SopB (SopB) or pEGFP-N2-SopBc/s (SopBc/s) at various time points after the shift to 32 °C. Endoglycosidase H (Endo H)-treated (+) and mock-treated (−) samples are indicated. The mobility of the Endo H-resistant (R; upper band) and -sensitive (S; lower band) forms of the protein is indicated. The boxes in B and C indicate the different Endo H sensitivity pattern exhibited by SopB-transfected cells. Actin immunoblotting is included as a loading control.
Mentions: To monitor the effect of SopB on VSVG trafficking, 293T cells were cotransfected with ts045-VSVG-GFP and either vector, SopB or SopBc/s. Cells were shifted to 40 °C overnight before cycloheximide was added to inhibit further protein synthesis and cells were shifted to 32 °C for various lengths of time to monitor VSVG transport. The vector- and SopBc/s-transfected cells exhibited similar behaviour, namely, that 1 h after the temperature shift the majority of the VSVG protein is Endo H-resistant and therefore has reached the Golgi (Figure 4). In contrast, cells transfected with SopB, show VSVG sensitivity to Endo H up to 2 h after the temperature shift, indicating that, in these cells, some of the VSVG protein remains localized to the ER (Figures 4B and 4C). Therefore, in the presence of SopB the transport of VSVG between the ER and Golgi is inhibited or delayed. The phosphatidylinositol phosphatase activity of SopB is important for this delay in transport between the ER and Golgi.

Bottom Line: Type III effectors interact with the host cell endocytic pathway to aid replication.We investigated whether Salmonella effector proteins may also interact with the host's exocytic pathway.The 4-phosphatase activity of SopB was crucial to its effect on exocytosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Purdue University , West Lafayette, IN 47907, USA.

ABSTRACT
Salmonella enterica pathogenesis is dependent on its ability to enter and replicate inside host cells. Replication occurs inside the Salmonella-containing vacuole (SCV), a vacuolar compartment that is modified by bacterial effectors secreted through the two type III secretion systems (T3SS-1 and T3SS-2). Type III effectors interact with the host cell endocytic pathway to aid replication. We investigated whether Salmonella effector proteins may also interact with the host's exocytic pathway. A secreted alkaline phosphatase (SEAP) assay indicated three Salmonella effectors inhibited the secretory pathway, although only Salmonella outer protein B (SopB) was confirmed to block exocytosis using a vesicular stomatitis virus glycoprotein-green fluorescent protein (VSVG-GFP) transport assay. The 4-phosphatase activity of SopB was crucial to its effect on exocytosis. The interaction with the secretory pathway could potentially be important for providing replicating Salmonella with nutrients, contributing membrane material necessary for SCV biogenesis, altering antibacterial peptide/protein secretion or manipulating cell surface proteins important in the host response to infection.

No MeSH data available.


Related in: MedlinePlus