Assessment of the Functional Regions of the Superantigen Staphylococcal Enterotoxin B

Abstract

The functional activity of superantigens is based on capacity of these microbial proteins to bind to both the β-chain of the T cell receptor (TcR) and the major histocompatibility complex (MHC) class II dimer. We have previously shown that a subset of the bacterial superantigens also binds to a membrane protein, designated p85, which is expressed by renal epithelial cells. This binding activity is a property of SEB, SEC1, 2 and 3, but not SEA, SED, SEE or TSST. The crystal structure of the tri-molecular complex of the superantigen staphylococcal enterotoxin B (SEB) with both the TcR and class II has previously been reported. However, the relative contributions of regions of the superantigen to the overall functional activity of this superantigen remain undefined. In an effort to better define the molecular basis for the interaction of SEB with the TcR β-chain, we report studies here which show the comparative contributions of amino- and carboxy-terminal regions in the superantigen activity of SEB. Recombinant fusion proteins composed of bacterial maltose-binding protein linked to either full-length or truncated toxins in which the 81 N-terminal, or 19 or 34 C-terminal amino acids were deleted, were generated for these studies. This approach provides a determination of the relative strength of the functional activity of the various regions of the superantigen protein.

Association between the accessory gene regulator (agr) locus and the presence of superantigen genes in clinical isolates of methicillin-resistant Staphylococcus aureus

“…As MacFadden et al [ 16 ], Singer et al [ 17 ], and Kurenbach et al [ 18 ] studies prove this notion, differences in the patterns of climate can lead to widespread changes in antibiotic resistance patterns. Consistent with our results, Zhang et al [ 19 ] demonstrated the effects of various environmental conditions on antibiotic resistance and virulence factors in bacteria. Agr typing as a convenient virulence typing method could contribute to a more precise understanding of the pathogenesis and epidemiology of staphylococcal infections [ 20 ].…”

“…Whereas 0% (0 isolates) and 16.66% [ 1 ] of MSSA strains were detected in aspiration and sputum respectively. In Group 2, the most prevalent MRSA isolates were detected in blood 72.13% (44) and wound 46.34% [ 19 ], whereas MSSA isolates were identified in aspiration 26.66% [ 4 ] and sputum 10% [ 9 ] respectively, Table 1 .…”

Binding of Staphylococcal Enterotoxin B (SEB) to B7 Receptors Triggers TCR- and CD28-Mediated Inflammatory Signals in the Absence of MHC Class II Molecules

“…( 24 ) demonstrated that SEB is able to directly interact with B7 molecules also in the absence of MHC class II molecules. These data together with the observation that the regions of SEB involved in binding B7 and TCR are distal ( 11 , 16 , 23 , 24 , 56 ), indicate that the binding of SEB to B7 molecules on APCs and to CD28 on T cells may suffice for a productive engagement of the TCR on T cells. Indeed, MHC class II-independent stimulation of T cells by SEB was previously reported, although the alternative SEB binding receptors were not identified ( 57 – 59 ).…”

Genotype and enterotoxigenicity of Staphylococcus epidermidis isolate from ready to eat meat products

“…However, based on current knowledge it cannot be definitely resolved whether these mutations can alter biological activity of SEC epi if referred to S. aureus SECs. Data on structure/function relations in SE family in many cases are still insufficient to precisely identify residues involved in mitogenic activity of SEs (Zhang and Rogers, 2013). Moreover, site-specific mutagenesis revealed substantial differences within SEs in term of epitopes responsible for mitogenic activity (Briggs et al, 1997).…”