Bass hepcidin synthesis, solution structure, antimicrobial activities and synergism, and in vivo hepatic response to bacterial infections
Bass hepcidin synthesis, solution structure, antimicrobial activities and synergism, and in vivo hepatic response to bacterial infections
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DOI：
10.1074/jbc.m411154200
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发表时间：
2005-03-11
影响因子：
4.8
通讯作者：
Westerman, ME
中科院分区：
文献类型：
--
作者：
Lauth, X;Babon, JJ;Westerman, ME
根据对大肠杆菌的抑菌活性，从杂交花叶鱼(Morone Chrysopsx Morone Saxatilis)的鳃中分离纯化出抗菌活性较高的海普西丁。这个21个氨基酸的多肽有8个半胱氨酸参与4个二硫键，与人海普西丁非常相似，人海普西丁是一种具有铁调节特性的抗菌肽。为了深入了解黑鱼海普西丁在鱼类先天免疫中的潜在作用(S)，我们合成了该多肽，并对其体外抗菌活性进行了表征，用核磁共振确定了其溶液结构，并定量研究了黑鲍鱼感染鱼类病原体--猪链球菌或沙门氏气单胞菌后体内肝脏基因的表达。它的结构与人海普西丁非常相似，包括存在一个反平行的β-折叠，一个保守的二硫键模式，以及一个罕见的邻位二硫键。合成的黑鲍鱼海普西丁在体外对革兰氏阴性病原菌和真菌具有活性，但对主要革兰氏阳性病原菌和单一酵母菌没有活性。海普西丁在杀菌浓度下不具溶血性，其比活性低于吗啡肽，后者是一种广谱、两亲性、α-螺旋、抗微生物多肽，主要在鲟鱼的组织中表达。海普西丁和吗啡黄素的体外杀菌活性有很好的协同作用。在感染革兰氏阳性(S.iniae)或革兰氏阴性(A.salmonicida)病原体后数小时内，黑鱼肝脏中海普西丁基因的表达显著增加，并在感染后24-48h比基线高出4-5个数量级。我们的结果表明，海普西丁在鳕鱼的抗菌防御中起着关键作用，其功能在鱼类和人类之间具有潜在的保守性。
Bass hepcidin was purified from the gill of hybrid striped bass ( Morone chrysops x Morone saxatilis) based on antimicrobial activity against Escherichia coli. This 21-amino acid peptide has 8 cysteines engaged in 4 disulfide bonds and is very similar to human hepcidin, an antimicrobial peptide with iron regulatory properties. To gain insight into potential role(s) of bass hepcidin in innate immunity in fish, we synthesized the peptide, characterized its antimicrobial activities in vitro, determined its solution structure by NMR, and quantified hepatic gene expression in vivo following infection of bass with the fish pathogens, Streptococcus iniae or Aeromonas salmonicida. Its structure is very similar to that of human hepcidin, including the presence of an antiparallel beta-sheet, a conserved disulfide-bonding pattern, and a rare vicinal disulfide bond. Synthetic bass hepcidin was active in vitro against Gram- negative pathogens and fungi but showed no activity against key Gram- positive pathogens and a single yeast strain tested. Hepcidin was non-hemolytic at microbicidal concentrations and had lower specific activity than moronecidin, a broad spectrum, amphipathic, alpha-helical, antimicrobial peptide constitutively expressed in bass gill tissue. Good synergism between the bacterial killing activities of hepcidin and moronecidin was observed in vitro. Hepcidin gene expression in bass liver increased significantly within hours of infection with Gram- positive ( S. iniae) or Gram- negative ( A. salmonicida) pathogens and was 4 - 5 orders of magnitude above base-line 24-48 h post-infection. Our results suggest that hepcidin plays a key role in the antimicrobial defenses of bass and that its functions are potentially conserved between fish and human.