Identification of the functional region on the superantigen Yersinia pseudotuberculosis‐derived mitogen responsible for induction of lymphocyte proliferation by using synthetic peptides

Abstract

Yersinia pseudotuberculosis-derived mitogen (YPM)is the unique Gram-negative bacillary superantigen known. In order to identify the regions on the YPM molecule involved in its superantigenic activity, seven overlapping peptides of the entire YPM molecule were synthesized and tested to evaluate their effects on the YPM-induced proliferation of human peripheral blood lymphocytes. A peptide corresponding to the N-terminal amino acid sequence (1-23) was found to inhibit YPM-induced lymphocyte proliferation in a concentration-dependent manner. The N-terminal peptide was found to show no inhibition of the proliferation induced by the other superantigen (staphylococcal enterotoxin B) or the other T-cell mitogen pertussis toxin, indicating that the inhibition is specific to YPM-induced proliferation. Thus, we have identified the N-terminal region (1-23) of the YPM as one of the functional regions responsible for its superantigenic activity.

Purification, characterization and cloning of a novel variant of the superantigen Yersinia pseudotuberculosis‐derived mitogen

“…As these two superantigen molecules possess the same function, the low homology suggests that the central region is not important for the function of both YPM molecules. In our previous study, it has been identified through competition studies by using synthetic peptides that a region of YPMa encompassing amino acid residues 1 through 23 is involved in the induction of human PBMC proliferation [16]. This is in agreement with the higher homology of the N‐terminal portion.…”

“…Proliferative response was measured with human PBMC as described previously [16]. Vβ repertoire specificity was analyzed by a semiquantitative PCR method as described previously [1].…”

Y. enterocolitica and Y. pseudotuberculosis

“…The molecular mechanism by which YPM interacts with its two ligands, TcR and MHC class II molecules, is poorly known. By testing the blocking effect of synthetic peptides on YPM-triggered lymphocyte proliferation, it was found that a peptide corresponding to the first 23 amino acids of the Y. pseudotuberculosis superantigen was the best inhibitor; however, this peptide corresponding to the N-terminus region of the molecule only inhibited cell proliferation by 50% (Yoshino et al, 1996). Subsequently, mutational analysis of YPM revealed that the amino acids involved in ligand interactions are in fact scattered along the polypeptide chain rather than clustered into domains, and that two cysteine residues, located at positions 32 and 129, form a disulfide bridge that is critical for the biological activity of YPM (Ito et al, 1999).…”

T cell epitopes of the La/SSB autoantigen in humanized transgenic mice expressing the hLa class II haplotype DRB1*0301/DQB1*0201

“…Computer analysis was performed using the SYFPEITHI (34) and ProPred (35) programs to find similarities between the hLa epitope sequences and putative DR3 binding motifs. Probable DRB1*0301 binding registers for each of the DR3-restricted epitopes uncovered in this study were identified ( Figure 4A), indicating that the most conserved residue is the p4 position, consisting of an aspartic acid (hLa [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] , hLa 55-72 , hLa 151-168 , hLa 211-228 , hLa [241][242][243][244][245][246][247][248][249][250][251][252][253][254][255][256][257][258] , and hLa 313-330 ) or conservatively substituted glutamic acid (hLa [46][47][48][49][50][51][52][53][54] ), in 7 of 7 epitopes, followed by p1 (in 5 of 7 epitopes), p6 (in 4 of 7 epitopes), and p9 (in 3 of 7 epitopes).…”

“…Human HLA-transgenic mice have been used to successfully study HLA-restricted T cell responses of multiple human autoantigens (18,19) and to discover neoepitopes of tumor antigens (20). This technology is particularly useful in HLA-transgenic models that lack spontaneous disease, since chronic inflammatory processes are known to severely compromise T cell responsiveness and have hampered the ex vivo study of T cells from human SLE patients.…”