Nguyen Mai Tuyet, Beck Jürgen, Lue Hongqi, Fünfzig Helge, Kleemann Robert, Koolwijk Pieter, Kapurniotu Aphrodite, Bernhagen Jürgen
Division of Biochemistry and Molecular Cell Biology, Institute of Biochemistry, University Hospital RWTH Aachen, D-52074 Aachen, Germany.
J Biol Chem. 2003 Sep 5;278(36):33654-71. doi: 10.1074/jbc.M301735200. Epub 2003 Jun 9.
Macrophage migration inhibitory factor (MIF) is a cytokine that participates in the host inflammatory response. A Cys-Xaa-Xaa-Cys (CXXC)-based thiol-protein oxidoreductase activity of MIF is associated with certain biological functions. Peptides spanning the CXXC region of thiol-protein oxidoreductases retain some biochemical properties of the full-length protein. We report on the characterization of CXXC-spanning MIF-(50-65) and its serine variant, C57S/C60S-MIF-(50-65). Following disulfide-mediated cyclization, MIF-(50-65) adapted a beta-turn conformation comparable with that of beta-turn-containing cyclo-57,60-[Asp57,Dap60]MIF-(50-65). MIF-(50-65) had a redox potential E'0 of -0.258 V and formed mixed disulfides with glutathione and cysteine. MIF-(50-65) but not C57S/C60S-MIF-(50-65) had oxidoreductase activity in vitro. Intriguingly, MIF-(50-65) exhibited MIF-like cellular activities. The peptide but not its variant had glucocorticoid overriding and proliferation-enhancing activity and stimulated ERK1/2 phosphorylation. MIF-(50-65) and its variant bound to the MIF-binding protein JAB1 and enhanced cellular levels of p27Kip1. As the peptide and its variant were endocytosed at similar efficiency, sequence 50-65 appears sufficient for the JAB1-related effects of MIF, whereas other activities require CXXC. Cyclo-57,60-[Asp57,Dap60]MIF-(50-65) activated ERK1/2, indicating that CXXC-dependent disulfide and beta-turn formation is associated with an activity-inducing conformation. We conclude that CXXC and sequence 50-65 are critical for the activities of MIF. MIF-(50-65) is a surprisingly short sequence with MIF-like functions that could be an excellent molecular template for MIF therapeutics.
巨噬细胞移动抑制因子（MIF）是一种参与宿主炎症反应的细胞因子。MIF基于半胱氨酸-任一氨基酸-任一氨基酸-半胱氨酸（CXXC）的硫醇蛋白氧化还原酶活性与某些生物学功能相关。跨越硫醇蛋白氧化还原酶CXXC区域的肽保留了全长蛋白的一些生化特性。我们报告了跨越CXXC区域的MIF-(50 - 65)及其丝氨酸变体C57S/C60S-MIF-(50 - 65)的特性。在二硫键介导的环化作用后，MIF-(50 - 65)呈现出与含β-转角的环化-57,60-[天冬氨酸57,二氨基丙酸60]MIF-(50 - 65)相当的β-转角构象。MIF-(50 - 65)的氧化还原电位E'0为-0.258 V，并与谷胱甘肽和半胱氨酸形成混合二硫键。MIF-(50 - 65)在体外具有氧化还原酶活性，而C57S/C60S-MIF-(50 - 65)则没有。有趣的是，MIF-(50 - 65)表现出类似MIF的细胞活性。该肽而非其变体具有糖皮质激素拮抗和增殖增强活性，并刺激ERK1/2磷酸化。MIF-(50 - 65)及其变体与MIF结合蛋白JAB1结合，并提高细胞中p27Kip1的水平。由于该肽及其变体以相似的效率被内吞，序列50 - 65似乎足以产生MIF与JAB1相关的效应，而其他活性则需要CXXC。环化-57,60-[天冬氨酸57,二氨基丙酸60]MIF-(50 - 65)激活ERK1/2，表明CXXC依赖的二硫键和β-转角形成与一种活性诱导构象相关。我们得出结论，CXXC和序列50 - 65对MIF的活性至关重要。MIF-(50 - 65)是一个具有类似MIF功能的惊人短序列，可能是MIF治疗的优秀分子模板。
