Biological analysis of the deletion mutants of Staphylococcal enterotoxin C2

Abstract

To investigate the functional domains involved in the biological activity of staphylococcal enterotoxin (SEC2), a series of SEC2 mutants were constructed. Deletion of the last 77 amino acids at the C-terminus of SEC2 did not affect its native superantigen and fever activities, and further removal of the C-terminal residues reduced SEC2 activities significantly. On the other hand, the mutants lacking 18 or more N-terminal residues severely impaired superantigen activity. These data indicated that the functional regions for the biological activities of SEC2 were confined to N-terminal domain, further implied that the proper three-dimensional structure of SEC2 is not needed for its biological activities. Our results deliver valuable information that it is possible to design new SEC2 immunotherapeutic agents which have the superantigen activity and low molecular weight for permeability.

T-cell proliferation and antitumour activities of a truncated mutant of staphylococcal enterotoxin C2 with decreased cytokine secretion

“…Our previous study found that the first 11 N-terminal residues of SEC2 could be deleted without affecting its mitogenicity and pyrogenicity, whereas deleting the first 18 N-terminal residues of SEC2 led to a substantial loss of its superantigen activity (Wang et al, 2009). Hoffmann et al (1994) found that the deletion of aa 1-13 of SEC1 did not affect its T-cell proliferation activity.…”

“…Our previous study showed that aa 163-239 were not required for the T-cell proliferation and pyrogenic activities, whilst aa 113-162 were important for both activities (Wang et al, 2009). The present study further showed that aa 129-162 are not required for the T-cell proliferation activity but are important for the pyrogenic activity of SEC2.…”

“…In our previous study, aa were not required for the T-cell proliferation activity of SEC2 (Wang et al, 2009). The region of SEC2 from aa 129 to 163 is composed of was injected intravenously at a dose of 10 mg kg "1 in PBS.…”

“…Tumour cell death induced by Tcell cytotoxicity (superantigen-dependent cellular cytotoxicity) was evaluated by an MTT assay (Wang et al, 2009). Briefly, murine splenocytes were used as effector cells and the murine hepatoma cell line Hepa1-6 was used as the target cells.…”

“…For the three SEC subtypes, Hoffmann et al (1994) found that the deletion of aa 1-13 did not affect the stimulatory activity of SEC1 on T-cell proliferation, whereas further deletion of the protein inhibited its T-cell proliferative activity. Moreover, our previous study indicated that deletion of the C-terminal 77 or N-terminal 11 aa had little effect on the T-cell proliferation and pyrogenic activities of SEC2; however, deletion of the C-terminal 127 or N-terminal 18 aa significantly depressed its activities (Wang et al, 2009). …”