An unusual structural motif of antimicrobial peptides containing end-to-end macrocycle and cystine-knot disulfides
An unusual structural motif of antimicrobial peptides containing end-to-end macrocycle and cystine-knot disulfides
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DOI：
10.1073/pnas.96.16.8913
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发表时间：
1999-08-03
影响因子：
11.1
通讯作者：
Chiu, KW
中科院分区：
文献类型：
--
作者：
Tam, JP;Lu, YA;Chiu, KW
从咖啡树中分离到4个29-31个残基的大环胱氨酸结肽：Kalata、环素A和环素B(CIRA和CIRB)以及环孢菌素，但它们的生理功能尚未确定。通过化学合成制备的这些大环和它们的10个类似物对9种微生物进行了测试。KALATA和CIRA对革兰氏阳性金黄色葡萄球菌的最低抑菌浓度约为0.2mM，对大肠埃希菌和铜绿假单胞菌等革兰氏阴性菌相对无效。然而，CIRB和Cyclopsychotride仅对革兰氏阳性和革兰氏阴性细菌有效。CIRB对大肠杆菌表现出较强的抑制活性，最小抑菌浓度为0.41mU·M。4个环肽对两种真菌KEFYR和热带念珠菌均有中等活性，但对白色念珠菌无活性。这些大环具有细胞毒性，裂解人红细胞，致死量为400mU·M。用酮醛修饰Kalata中的Arg残基显著降低其对金黄色葡萄球菌的活性，而在CIRA中阻断Arg则没有显著作用。两个二硫键变异体及其混杂的二硫键异构体表现出与其天然多肽相似的抗菌谱和效力，然而，在高盐(100 MM NaC L)分析中，这些大环肽中几乎没有天然或类似物保持抗菌活性，这些结果表明大环肽具有特定而有效的抗菌活性，这种活性依赖于盐，并且它们与微生物表面的初始相互作用可能是静电的，这一效应在抗菌肽的防御中常见。此外，它们的端到端环结构与半胱氨酸结基序代表了抗菌素的分子结构，并可能为新型多肽抗生素的设计提供有用的模板。
Four macrocyclic cystine-knot peptides of 29-31 residues, kalata, circulin A and B (CirA and CirB), and cyclopsychotride, have been isolated from coffee plants but have undetermined physiological functions. These macrocycles and 10 of their analogs prepared by chemical synthesis were tested against nine strains of microbes. Kalata and CirA were specific for the Gram-positive Staphylococcus aureus with a minimum inhibition concentration of approximate to 0.2 mu M. They were relatively ineffective against Gram-negative bacteria such as Escherichia coli and Pseudomonas aeruginosa. However, CirB and cyclopsychotride mere active against both Gram-positive and Gram-negative bacteria. In particular, CirB showed potent activity against E. coli with a minimum inhibitory concentration of 0.41 mu M. All four cyclic peptides were moderately active against two strains of fungi, Candida kefyr and Candida tropicalis, but were inactive against Candida albicans, These macrocycles are cytotoxic and lysed human red blood cell with a lethal dose 50% of 400 mu M. Modifying the Arg residue in kalata with a keto aldehyde significantly reduced its activity against S. aureus whereas blocking the arg in CirA produced no significant effect. The two-disulfide variants and their scrambled disulfide isomers exhibited antimicrobial profiles and potency similar to their native peptides, However, in high-salt assays (100 mM NaCl), few of these macrocyclic peptides, natives or analogs, retained antimicrobial activity, These results show that the macrocyclic peptides possess specific and potent antimicrobial activity that is salt-dependent and that their initial interactions with the microbial surfaces may be electrostatic, an effect commonly found in defensin antimicrobial peptides, Furthermore, their end-to-end cyclic structure with a cystine-knot motif represents a molecular structure of antimicrobials and may provide a useful template for the design of novel peptide antibiotics.