spa

Fig1. Model of S. aureus interaction with osteoblasts. Engagement of S. aureus protein A with osteoblast TNFR-1 results in IkB degradation and NFκB activation.

What is SpA protein?

Staphylococcus aureus protein A (SpA) is a cell-wall-bound pathogenicity factor from the Gram-positive bacteria Staphylococcus aureus that comprises of 4 or 5 homologous immunoglobulin (Ig)-binding domains (E, D, A, B, and C) of 56–61 residues followed by a polymorphic variable repeat region, Xr, and a conserved region, Xc, which includes a cell-wall attachment sequence

Because of their small size and immunoglobulin (IgG)-binding activities, domains of protein A are targets for protein engineering efforts and for the development of computational approaches for de novo protein folding.

What is the function of SpA protein?

Plays a role in the inhibition of the host innate and adaptive immune responses. Among its 4 or 5 domains, the interaction between domain D of SpA and the Fab 2A2 from a human IgM antibody is noteworthy. In turn, Staphylococcus aureus is protected from phagocytic killing via inhibition of Ig Fc region. In addition, the host elicited B-cell response is prevented due to a decrease of antibody-secreting cell proliferation that enter the bone marrow, thereby decreasing long-term antibody production. Inhibits osteogenesis by preventing osteoblast proliferation and expression of alkaline phosphatase, type I collagen, osteopontin and osteocalcin. Acts directly as a pro-inflammatory factor in the lung through its ability to bind and activate tumor necrosis factor alpha receptor 1/TNFRSF1A (By similarity).

Application of SpA Protein

SpA has a wide range of biochemical, biotechnological, and is most commonly used in test methods such as immunoprecipitation, enzyme-linked immunosorbent assay, and Western blotting. Because of its ability to bind the Fab and Fc fragments of a wide range of mammalian immunoglobulins, it can be used as a carrier or affinity chromatography medium for antibodies. Surface display of SPA has an application in immuno-precipitation of IgG-antigen complex. And it is also used for one-step and high efficiency purification of IgG. SpA also directly binds to the B-cells preventing initiation of infectious diseases as well as having a role in the development of various autoimmune diseases like Rheumatoid arthritis (RA) and Idiopathic thrombocytopenic purpura (ITP). SpA gene typing has been used to study relatedness of S. aureus isolates.

Case Study 1: Helen L. Shuttleworth, 1987

Fig1. Comparison of protein A yields for SPA plasmids in various Eschenkhia coli hosts.

Case Study 2: Marisa I Gómez, 2006

Fig2. Epithelial cells were incubated with GST protein A fusions and binding of the different protein constructs to the surface quantified by flow cytometry.

spa has several biochemical functions, for example, . Some of the functions are cooperated with other proteins, some of the functions could acted by spa itself. We selected most functions spa had, and list some proteins which have the same functions with spa. You can find most of the proteins on our site.

spa has direct interactions with proteins and molecules. Those interactions were detected by several methods such as yeast two hybrid, co-IP, pull-down and so on. We selected proteins and molecules interacted with spa here. Most of them are supplied by our site. Hope this information will be useful for your research of spa.