Mutagenesis, biochemical, and biophysical characterization of Mycoplasma arthritidis-derived mitogen.
Mutagenesis, biochemical, and biophysical characterization of Mycoplasma arthritidis-derived mitogen.
复制标题
关节炎支原体衍生丝裂原的诱变、生化和生物物理特征。
DOI：
10.1016/j.molimm.2006.04.010
复制
发表时间：
2007
影响因子：
3.6
通讯作者：
Mourad,Walid
中科院分区：
文献类型：
--
作者：
Li,Hongmin;Zhao,Yiwei;Guo,Yi;Vanvranken,SandraJ;Li,Zhong;Eisele,Leslie;Mourad,Walid
Mycoplasma arthritidis-derived mitogen (MAM) is a superantigen (SAg) that can activate large fractions of T cells bearing particular TCR Vβ elements. Here we report the mutagenesis, biochemical and biophysical studies on the dimerization of MAM in solution. Our studies showed that although MAM mainly exists as a monomer in solution, a small percentage of MAM molecules form homodimer at high protein concentration, regardless of the presence of Zn2+. A distinct peak corresponding to a MAM homodimer was detected in the presence of EDTA, using both chemical cross-linking and analytical ultracentrifugation methods. Further mutagenesis studies revealed that single mutation of residues at the interface of the crystallographic dimer of MAM does not significantly affect the dimerization of MAM in solution. Circular dichroism (CD) analysis indicated that addition of Zn2+does not induce conformational changes of MAM from its apo-state. Thermal denaturation experiments indicated that addition of Zn2+to MAM solution resulted in a decrease of melting point (Tm), whereas addition of EDTA did not affect the Tmof MAM. These results imply that there is no defined Zn2+-binding site on MAM.
