Effects of Zn2+and Zn2+-coordinating glutamic acid residues on the superantigenic activities of staph-ylococcal enterotoxin C2 / 中华微生物学和免疫学杂志

ABSTRACT

Objective To investigate the role of Zn 2+and Zn2+-coordinating glutamic acid residues ( 71Glu and 80Glu ) in the superantigenic activities of staphylococcal enterotoxin C2 ( SEC2 ) .Methods Over-lap PCR was used to amply genes encoding recombinant mutant proteins rSEC 2 ( E71A), rSEC2 (E80A) and rSEC2 (E71A/E80A).The mutant proteins were expressed in E.coli BL21 (DE3) and puri-fied by affinity chromatography .The differences of biological activities between rSEC 2 and its mutants were compared in vitro.The effects of Zn 2+on the superantigenic activities of rSEC 2 were evaluated by analyzing the proliferation of splenic lymphocytes in the presence or absence of ethylenediaminetetraacetic acid ( EDTA) .Results The substitution of glutamic acid residue at position 71 and 80 by alanine residue had no significant effects on the superantigenic activities and the conformational stability of rSEC 2 mutants.How-ever, traces of Zn2+(10μmol/L) could significantly enhance rSEC2-induced proliferation of splenic lympho-cytes, and only certain amount of Zn 2+could completely restore rSEC2-induced proliferation in the presence of EDTA.Conclusion This study indicated that mutations at Zn 2+-coordinating glutamic acid residues had no significant effects on the conformational stability and the superantigenic activities of SEC 2.Zn2+might play a role in regulating the superantigenic activities of SEC 2 through some indirect ways .