Crystal and solution structures of a novel antimicrobial peptide from Chrysomya megacephala,Acta Crystallographica Section D

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Crystal and solution structures of a novel antimicrobial peptide from Chrysomya megacephala
Acta Crystallographica Section D ( IF 2.6 ) Pub Date : 2021-06-18 , DOI: 10.1107/s2059798321004629
Chengliang Xiao ₁ , Zaiyu Xiao ₁ , Cuifang Hu ₂ , Jie Lu ₁ , Liwei Cui ₃ , Yang Zhang ₁ , Yujie Dai ₂ , Qinghua Zhang ₂ , Sheng Wang ₁ , Wei Liu ₃

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Antimicrobial peptides (AMPs) are small amphipathic peptides that exhibit bactericidal activity against a wide range of pathogenic microorganisms and are considered to be potential substitutes for antibiotics effective against microbial infection. PSK, an 84-amino-acid AMP recently isolated from Chrysomya megacephala larvae, probably belongs to the mitochondrial ATPase inhibitor family according to its sequence. No member of this family from an insect has been structurally characterized to date. In this study, the crystal structure of full-length PSK determined by molecular replacement using an ab initio modeled ensemble as a search model and a solution structure obtained from small-angle X-ray scattering (SAXS) measurements are reported. The crystal structure reveals a distinct fold compared with those of homologous peptides, in that PSK comprises two antiparallel α-helices rather than a single long helix, which is in good agreement with the SAXS-based ab initio model. However, the peptide exists as a monomer in solution, even though a stable dimer was observed in the crystal structure. This apparent contradiction may reflect different oligomerization states that may be implicated in its bioactivity. The data presented here have established a solid basis for further mechanistic studies of this novel insect AMP.

中文翻译：

一种来自巨头金蝇的新型抗菌肽的晶体和溶液结构

抗菌肽 (AMP) 是一种小的两亲性肽，对多种病原微生物表现出杀菌活性，被认为是有效对抗微生物感染的抗生素的潜在替代品。PSK 是一种最近从巨头金蝇幼虫中分离出来的 84 个氨基酸的 AMP ，根据其序列可能属于线粒体 ATP 酶抑制剂家族。迄今为止，尚未对昆虫的这个家族的任何成员进行结构表征。在这项研究中，全长 PSK 的晶体结构通过使用ab initio 的分子置换确定模型集成作为搜索模型和从小角度 X 射线散射 (SAXS) 测量获得的解决方案结构报告。与同源肽相比，晶体结构显示出明显的折叠，因为 PSK 包含两个反平行的 α-螺旋而不是单个长螺旋，这与基于 SAXS 的ab initio模型非常一致。然而，即使在晶体结构中观察到稳定的二聚体，该肽仍作为单体存在于溶液中。这种明显的矛盾可能反映了可能与其生物活性有关的不同低聚状态。这里提供的数据为进一步研究这种新型昆虫 AMP 的机理奠定了坚实的基础。

更新日期：2021-07-02

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