The interaction between Staphylococcus aureus SdrD and desmoglein 1 is important for adhesion to host cells

Abstract

Staphylococcus aureus is known as a frequent colonizer of the skin and mucosa. Among bacterial factors involved in colonization are adhesins such as the microbial surface components recognizing adhesive matrix molecules (MSCRAMMs). Serine aspartate repeat containing protein D (SdrD) is involved in adhesion to human squamous cells isolated from the nose. Here, we identify Desmoglein 1 (Dsg1) as a novel interaction partner for SdrD. Genetic deletion of sdrD in S. aureus NCTC8325-4 through allelic replacement resulted in decreased bacterial adherence to Dsg1- expressing HaCaT cells in vitro. Complementary gain-of-function was demonstrated by heterologous expression of SdrD in Lactococcus lactis, which increased adherence to HaCaT cells. Also ectopic expression of Dsg1 in HEK293 cells resulted in increased adherence of S. aureus NCTC8325-4 in vitro. Increased adherence of NCTC8325-4, compared to NCTC8325-4ΔsdrD, to the recombinant immobilized Dsg1 demonstrated direct interaction between SdrD and Dsg1. Specificity of SdrD interaction with Dsg1 was further verified using flow cytometry and confirmed binding of recombinant SdrD to HaCaT cells expressing Dsg1 on their surface. These data demonstrate that Dsg1 is a host ligand for SdrD.

Serine-Aspartate Repeat Protein D Increases Staphylococcus aureus Virulence and Survival in Blood

“…The approximately 3.5-fold higher rate of survival of the parent strain was not attributable to differences in bacterial growth rates between NCTC8325-4 and its isogenic mutant (see Fig. S1A in the supplemental material) (4). The SdrD-mediated increase in bacterial survival was also observed in mouse blood (Fig.…”

“…aureus NCTC8325-4 Δ sdrD , Lactococcus lactis MG1363 expressing SdrD ( sdrD -pMG36e), and L. lactis MG1363 expressing the empty vector (pMG36e) have been described previously (4). Moreover, the sdrD -pMG36e and pMG36e constructs (4) were used to complement NCTC8325-4 Δ sdrD through electroporation (100-Ω resistance, 25-μF capacitance, and 2.5-kV voltage).…”

“…aureus subsp. aureus sdrD -GFP reporter strain was described previously (4) and was subsequently used to assess sdrD expression during growth in TSB medium. An overnight culture of S.…”

“…aureus subsp. aureus NCTC8325-4 and the isogenic NCTC8325-4 Δ sdrD mutant were prepared for Western blotting as described previously (4). To assess the release of SdrD, the culture supernatant was filter sterilized (pore size, 0.22 μm) to remove intact bacterial cells and concentrated using an Amicon Ultra 50K centrifugal filter device (Millipore Corp., USA).…”

“…SdrD promotes the adherence of S. aureus to desquamated nasal epithelial cells (3) and to human keratinocytes in vitro (4) and contributes to abscess formation in vivo (5). …”