Solution structure of Alo-3:: A new knottin-type antifungal peptide from the insect Acrocinus longimanus
Solution structure of Alo-3:: A new knottin-type antifungal peptide from the insect Acrocinus longimanus
复制标题
DOI：
10.1021/bi035400o
复制
发表时间：
2003-12-16
期刊：
影响因子：
2.9
通讯作者：
Vovelle, F
中科院分区：
文献类型：
--
作者：
Barbault, F;Landon, C;Vovelle, F
昆虫肽是抗细菌和真菌的天然免疫的关键要素。这些分子具有显著的特性：高功效、低耐药性、有限的毒性和免疫原性。在这种情况下，我们正在研究几类肽，我们已经成功地确定了生物学上重要的肽类和小分子，这些肽类和小分子将提供一系列候选药物，用于治疗严重的、危及生命的、医院获得性感染和其他高医疗需求的病理。最近，我们从鞘翅目长顶瓢虫Acrocinus longimanus中分离到了一类新的抗真菌肽。三个同源肽，Alo-1，Alo-2，和Alo-3，具有80%以上的序列同一性和活性的光滑念珠菌酵母菌株进行了鉴定。Alo-3显示出对光滑念珠菌的最高活性，因此选择使用NMR光谱和分子建模进行结构测定。Alo-3含有六个半胱氨酸残基，形成三个二硫键。使用ARIA软件中的模糊二硫键限制评估半胱氨酸的配对，使我们能够确定Alo-3属于抑制剂胱氨酸结家族。它表现出结蛋白折叠的所有结构特征，即三链反平行β-折叠，具有将第一链连接到第二链的长柔性环和一系列转弯。据我们所知，Alo-3是第一个采用knottin折叠的昆虫抗菌肽。Alo-3对C.比Alo-1或Alo-2光滑。它没有带负电荷的残基，并在其表面上显示一个阳离子极，这可能是其抗真菌活性的原因。通过将Alo-3的结构与来自其他来源的也显示抗真菌活性的其他结构相关肽的结构进行比较，验证了这一发现。
Insect peptides are key elements of the innate immunity against bacteria and fungi. These molecules offer remarkable properties: high efficacy, a low probability of resistance, limited toxicity, and immunogenicity. In this context, we are investigating several classes of peptides, and we have been successful in identifying biologically important classes of peptides and small molecules that will provide a stream of drug candidates for treating severe, life-threatening, hospital-acquired infections and other pathologies of high medical need. Recently, we have isolated a new class of antifungal peptides from the coleopteran Acrocinus longimanus. Three homologous peptides, Alo-1, Alo-2, and Alo-3, with sequence identity above 80% and active against the Candida glabrata yeast strain were identified. Alo-3 displayed the highest activity against Candida glabrata and was thus chosen for structure determination using NMR spectroscopy and molecular modeling. Alo-3 contains six cysteine residues forming three disulfide bridges. The pairing of the cysteines was assessed using ambiguous disulfide restraints within the ARIA software, allowing us to establish that Alo-3 belongs to the inhibitor cystine-knot family. It exhibits all the structural features characteristic of the knottin fold, namely, a triple-stranded antiparallel beta-sheet with a long flexible loop connecting the first strand to the second strand and a series of turns. To our knowledge, Alo-3 is the first peptide from insects with antimicrobial activity adopting the knottin fold. Alo-3 shows a level of activity significantly higher against C. glabrata than Alo-1 or Alo-2. It has no negatively charged residues and displays on its surface a cationic pole that may account for its antifungal activity. This finding is validated by the comparison of the structure of Alo-3 with the structure of other structurally related peptides from other sources also showing antifungal activity.