Specific metallo-protein interactions and antimicrobial activity in Histatin-5, an intrinsically disordered salivary peptide
Specific metallo-protein interactions and antimicrobial activity in Histatin-5, an intrinsically disordered salivary peptide
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DOI：
10.1038/s41598-019-52676-7
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发表时间：
2019-11-21
影响因子：
4.6
通讯作者：
Barry, Bridgette A.
中科院分区：
文献类型：
--
作者：
McCaslin, Tyler G.;Pagba, Cynthia V.;Barry, Bridgette A.
组胺素-5（Hst-5）是一种参与宿主防御系统的抗微生物唾液蛋白。Hst-5已被提议结合功能相关的锌和铜，但由于其在水溶液中的无序构象，在结构研究中提出了挑战。在这里，我们使用圆二色性（CD）和紫外共振拉曼（UVRR）光谱来定义金属Hst-5在水溶液中的相互作用。含锌的Hst-5样品相对于在不存在锌的情况下观察到的谱带表现出移位的拉曼谱带。基于比较模型化合物和一个家庭的设计，锌结合β发夹，在Hst-5 UVRR光谱的改变归因于锌配位咪唑侧链。锌的加入也通过静电相互作用使酪氨酸芳环UVRR带发生位移。铜的添加没有这些影响。采用序列变体H18 A/H19 A;当与Hst-5相比时，该突变体具有较低的有效抗真菌活性。添加锌对该突变株的热稳定性影响不大。有趣的是，锌和铜除了转移组氨酸UVRR带的方式诊断金属配位。用K13 E/R22 G突变体获得的结果与用野生型获得的结果相似。这些实验表明，H18和H19有助于锌结合位点。在H18 A/H19 A突变体中，铜/锌结合位点的特异性丧失。实验暗示特异性锌结合在Hst-5的抗微生物活性中是重要的。
Histatin-5 (Hst-5) is an antimicrobial, salivary protein that is involved in the host defense system. Hst-5 has been proposed to bind functionally relevant zinc and copper but presents challenges in structural studies due to its disordered conformation in aqueous solution. Here, we used circular dichroism (CD) and UV resonance Raman (UVRR) spectroscopy to define metallo-Hst-5 interactions in aqueous solution. A zinc-containing Hst-5 sample exhibits shifted Raman bands, relative to bands observed in the absence of zinc. Based on comparison to model compounds and to a family of designed, zinc-binding beta hairpins, the alterations in the Hst-5 UVRR spectrum are attributed to zinc coordination by imidazole side chains. Zinc addition also shifted a tyrosine aromatic ring UVRR band through an electrostatic interaction. Copper addition did not have these effects. A sequence variant, H18A/H19A, was employed; this mutant has less potent antifungal activity, when compared to Hst-5. Zinc addition had only a small effect on the thermal stability of this mutant. Interestingly, both zinc and copper addition shifted histidine UVRR bands in a manner diagnostic for metal coordination. Results obtained with a K13E/R22G mutant were similar to those obtained with wildtype. These experiments show that H18 and H19 contribute to a zinc binding site. In the H18A/H19A mutant the specificity of the copper/zinc binding sites is lost. The experiments implicate specific zinc binding to be important in the antimicrobial activity of Hst-5.