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Secretome analysis defines the major role of SecDF in Staphylococcus aureus virulence.

Quiblier C, Seidl K, Roschitzki B, Zinkernagel AS, Berger-Bächi B, Senn MM - PLoS ONE (2013)

Bottom Line: Numerous Sec signal containing proteins involved in virulence were found to be decreased in the supernatant of the secDF mutant.Adhesion, invasion, and cytotoxicity of the secDF mutant were reduced in human umbilical vein endothelial cells.Virulence was significantly reduced using a Galleria mellonella insect model.

View Article: PubMed Central - PubMed

Affiliation: Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland.

ABSTRACT
The Sec pathway plays a prominent role in protein export and membrane insertion, including the secretion of major bacterial virulence determinants. The accessory Sec constituent SecDF has been proposed to contribute to protein export. Deletion of Staphylococcus aureus secDF has previously been shown to reduce resistance, to alter cell separation, and to change the expression of certain virulence factors. To analyse the impact of the secDF deletion in S. aureus on protein secretion, a quantitative secretome analysis was performed. Numerous Sec signal containing proteins involved in virulence were found to be decreased in the supernatant of the secDF mutant. However, two Sec-dependent hydrolases were increased in comparison to the wild type, suggesting additional indirect, regulatory effects to occur upon deletion of secDF. Adhesion, invasion, and cytotoxicity of the secDF mutant were reduced in human umbilical vein endothelial cells. Virulence was significantly reduced using a Galleria mellonella insect model. Altogether, SecDF is a promising therapeutic target for controlling S. aureus infections.

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Related in: MedlinePlus

Differential extracellular protein amounts in Newman ΔsecDF in comparison to the wild type Newman.Proteins identified to be significantly and more than two-fold changed in Newman ΔsecDF compared to the wild type Newman. The mean values of four independent experiments are shown with their standard deviation given, except for NWMN_1019 and ScpA, which were only found in two biological replicates. Proteins are colour coded according to the following categories: N-terminal Sec signal peptide (SP), LPXTG-motif, adhesive properties (MSCRAMM and SERAM), immune evasive properties, autolytic properties and membrane proteins. Proteins confirmed below by Western blot analysis are highlighted in bold. *, P<0.05; **, P<0.01; ***, P<0.001.
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pone-0063513-g001: Differential extracellular protein amounts in Newman ΔsecDF in comparison to the wild type Newman.Proteins identified to be significantly and more than two-fold changed in Newman ΔsecDF compared to the wild type Newman. The mean values of four independent experiments are shown with their standard deviation given, except for NWMN_1019 and ScpA, which were only found in two biological replicates. Proteins are colour coded according to the following categories: N-terminal Sec signal peptide (SP), LPXTG-motif, adhesive properties (MSCRAMM and SERAM), immune evasive properties, autolytic properties and membrane proteins. Proteins confirmed below by Western blot analysis are highlighted in bold. *, P<0.05; **, P<0.01; ***, P<0.001.

Mentions: A total of 230 S. aureus proteins were quantified and their putative localization was determined with different bioinformatics tools (Table 2, Table S1). Thirty-eight proteins had a predicted SP [37], 34 thereof were predicted Sec-type SPs [38]. These included seven cell wall proteins containing the LPXTG cell wall retention motif (SpA, SdrE, ClfA, IsdA, FnBPA, ClfB) [39], [40] or LysM domains (Sle1/Aaa) [41]. In Newman ΔsecDF, in comparison to the wild type Newman, the extracellular levels of 27 proteins were altered significantly by at least two fold increase (two proteins) or two fold decrease (25 proteins); 21 of these proteins contained a Sec-type SP (Figure 1). Of the six remaining proteins, three were membrane proteins; OatA and the LytR-CpsA-Psr proteins NWMN_0925 (SA0908) and MsrR [42], [43]. Furthermore, the SP containing, but Sec-independent enterotoxin A (SEA) and the delta hemolysin (Hld) were identified.


Secretome analysis defines the major role of SecDF in Staphylococcus aureus virulence.

Quiblier C, Seidl K, Roschitzki B, Zinkernagel AS, Berger-Bächi B, Senn MM - PLoS ONE (2013)

Differential extracellular protein amounts in Newman ΔsecDF in comparison to the wild type Newman.Proteins identified to be significantly and more than two-fold changed in Newman ΔsecDF compared to the wild type Newman. The mean values of four independent experiments are shown with their standard deviation given, except for NWMN_1019 and ScpA, which were only found in two biological replicates. Proteins are colour coded according to the following categories: N-terminal Sec signal peptide (SP), LPXTG-motif, adhesive properties (MSCRAMM and SERAM), immune evasive properties, autolytic properties and membrane proteins. Proteins confirmed below by Western blot analysis are highlighted in bold. *, P<0.05; **, P<0.01; ***, P<0.001.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3643904&req=5

pone-0063513-g001: Differential extracellular protein amounts in Newman ΔsecDF in comparison to the wild type Newman.Proteins identified to be significantly and more than two-fold changed in Newman ΔsecDF compared to the wild type Newman. The mean values of four independent experiments are shown with their standard deviation given, except for NWMN_1019 and ScpA, which were only found in two biological replicates. Proteins are colour coded according to the following categories: N-terminal Sec signal peptide (SP), LPXTG-motif, adhesive properties (MSCRAMM and SERAM), immune evasive properties, autolytic properties and membrane proteins. Proteins confirmed below by Western blot analysis are highlighted in bold. *, P<0.05; **, P<0.01; ***, P<0.001.
Mentions: A total of 230 S. aureus proteins were quantified and their putative localization was determined with different bioinformatics tools (Table 2, Table S1). Thirty-eight proteins had a predicted SP [37], 34 thereof were predicted Sec-type SPs [38]. These included seven cell wall proteins containing the LPXTG cell wall retention motif (SpA, SdrE, ClfA, IsdA, FnBPA, ClfB) [39], [40] or LysM domains (Sle1/Aaa) [41]. In Newman ΔsecDF, in comparison to the wild type Newman, the extracellular levels of 27 proteins were altered significantly by at least two fold increase (two proteins) or two fold decrease (25 proteins); 21 of these proteins contained a Sec-type SP (Figure 1). Of the six remaining proteins, three were membrane proteins; OatA and the LytR-CpsA-Psr proteins NWMN_0925 (SA0908) and MsrR [42], [43]. Furthermore, the SP containing, but Sec-independent enterotoxin A (SEA) and the delta hemolysin (Hld) were identified.

Bottom Line: Numerous Sec signal containing proteins involved in virulence were found to be decreased in the supernatant of the secDF mutant.Adhesion, invasion, and cytotoxicity of the secDF mutant were reduced in human umbilical vein endothelial cells.Virulence was significantly reduced using a Galleria mellonella insect model.

View Article: PubMed Central - PubMed

Affiliation: Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland.

ABSTRACT
The Sec pathway plays a prominent role in protein export and membrane insertion, including the secretion of major bacterial virulence determinants. The accessory Sec constituent SecDF has been proposed to contribute to protein export. Deletion of Staphylococcus aureus secDF has previously been shown to reduce resistance, to alter cell separation, and to change the expression of certain virulence factors. To analyse the impact of the secDF deletion in S. aureus on protein secretion, a quantitative secretome analysis was performed. Numerous Sec signal containing proteins involved in virulence were found to be decreased in the supernatant of the secDF mutant. However, two Sec-dependent hydrolases were increased in comparison to the wild type, suggesting additional indirect, regulatory effects to occur upon deletion of secDF. Adhesion, invasion, and cytotoxicity of the secDF mutant were reduced in human umbilical vein endothelial cells. Virulence was significantly reduced using a Galleria mellonella insect model. Altogether, SecDF is a promising therapeutic target for controlling S. aureus infections.

Show MeSH
Related in: MedlinePlus