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首页> 外文期刊>Biochemistry >Avian MRP126 Restricts Microbial Growth through Ca(II)-Dependent Zn(II) Sequestration
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Avian MRP126 Restricts Microbial Growth through Ca(II)-Dependent Zn(II) Sequestration

机译:禽MRP126通过Ca(II)依赖性Zn(II)隔离限制微生物生长

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The calgranulins form a class of S100 proteins in higher vertebrates that innate-immune cells release in abundance at infection sites. These proteins function by binding transition metal ions to prevent microbial pathogens from obtaining those essential nutrients. Mammals express three distinct members of this family: S100A8 (calgranulin A), S100A9 (calgranulin B, which hetero-oligomerizes with S100A8 to form calprotectin), and S100A12 (calgranulin C), that exhibit Ca(II)-dependent transition metal binding properties. Human calprotectin effectively sequesters Mn(II), Fe(II), Ni(II), and Zn(II), whereas human S100A12 selectively sequesters Zn(II) over these other metal ions. Birds and reptiles express a single calgranulin homologue named MRP126, which we reasoned could have properties more similar to those of either calprotectin or S100A12. Here we present the purification and biophysical characterization of recombinant chicken MRP126 and, to the best of our knowledge, provide the first assessment of the metal binding and antimicrobial properties of an avian MRP126. We show that MRP126 is a homodimer that selectively sequesters Zn(II) and restricts the growth of certain microbes. MRP126 binds Zn(II) at two canonical His(3)Asp sites. The presence of excess Ca(II) increases the affinity of the His(3)Asp sites from the low-nanomolar to the low-picomolar range, thereby enhancing antimicrobial activity. Chicken MRP126 also binds additional Zn(II) equivalents with low-nanomolar affinity at two nonconserved dicysteine sites and with high-nanomolar affinity using a histidine-rich C-terminal tail that is a hallmark of this Glade of calgranulins. Our results with chicken MRP126 suggest that Ca(II)-dependent Zn(II) sequestration was a role of the last common ancestor of calgranulin proteins, with mammalian calprotectin subsequently evolving a broader metal binding repertoire.
机译:钙粒蛋白在高等脊椎动物中形成一类 S100 蛋白,先天免疫细胞在感染部位大量释放。这些蛋白质通过结合过渡金属离子来阻止微生物病原体获得这些必需的营养物质。哺乳动物表达该家族的三个不同成员:S100A8(钙粒蛋白 A)、S100A9(钙粒蛋白 B,与 S100A8 异源寡聚形成钙卫蛋白)和 S100A12(钙粒蛋白 C),它们表现出 Ca(II) 依赖性过渡金属结合特性。人钙卫蛋白有效地螯合 Mn(II)、Fe(II)、Ni(II) 和 Zn(II),而人S100A12选择性地将 Zn(II) 螯合在这些其他金属离子上。鸟类和爬行动物表达一种名为MRP126的钙粒蛋白同系物,我们推断它可能具有与钙卫蛋白或S100A12更相似的特性。在这里,我们介绍了重组鸡MRP126的纯化和生物物理表征,并据我们所知,首次评估了禽MRP126的金属结合和抗菌特性。我们发现MRP126是一种选择性地螯合Zn(II)并限制某些微生物生长的同型二聚体。MRP126 在两个典型的 His(3)Asp 位点结合 Zn(II)。过量Ca(II)的存在增加了His(3)Asp位点从低纳摩尔到低皮摩尔范围的亲和力,从而增强了抗菌活性。Chicken MRP126 还在两个非保守的双胞胺位点以低纳摩尔亲和力结合额外的 Zn(II) 当量,并使用富含组氨酸的 C 末端尾部结合高纳摩尔亲和力,这是钙粒蛋白林间空地的标志。我们对鸡 MRP126 的结果表明,Ca(II) 依赖性 Zn(II) 隔离是钙颗粒蛋白最后一个共同祖先的作用,哺乳动物钙卫蛋白随后进化出更广泛的金属结合库。

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