INTRODUCTION Insect growth and metamorphosis are strictly dependent on the structural changes that occur in chitin containing tissues and organs. Chitin synthase catalyzes chitin polymerization by β-(1, 4) glycosidic linkage of N-acetyl-D-glucosamine (GlcNAc) monomers; the major component of insect cuticles. Targeting this enzyme could be a promising strategy to control insect pests while avoiding adverse effects on coexisting populations. Nikkomycin Z and polyoxins are commercially available fungal inhibitors known to bind to the nucleotide-binding sites of insects and fungal chitin synthase. But the binding mode of chitin synthase has not been explored to date as its structure is not available yet. METHODS To understand the structural features of the Chilo partellus chitin synthase enzyme (CpCHS), the three-dimensional (3D) structure of the CpCHS catalytic domain was modeled using ROBETTA webserver. The obtained model was used to investigate the binding mode of its substrate, uridine diphosphate-N-acetyl-D-glucosamine (UDP-GlcNAc), and inhibitors (nikkomycin Z and polyoxins) by molecular docking approach using Schrödinger Suite-Maestro v9.2. The docked complexes were further investigated for their interaction stability by performing molecular dynamics (MD) simulations using GROMACS v5.1.2. RESULTS Our study highlighted the significance of various interactions made by CHS residues present in the Walker-B loop and donor-binding motifs with the substrate (UDP-GlcNAc), and GEDR motif with an acceptor (GlcNAc). Also, the interactions of the QRRRW motif while forming chitin polymer were explored. We observed that the inhibitors exhibited good binding affinity with these motifs, indicated by their docking and binding affinity scores. CONCLUSION In vitro analysis suggested that nikkomycin Z showed higher inhibition of chitin synthase activity at a concentration of 2.5 μg.L-1. Our study provided insights into the crucial interactions of chitin synthase while designing inhibitors against insect pests.

中文翻译：

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对来自玉米茎螟的几丁质合酶底物和抑制剂的计算机结合谱分析和体外研究，Chilo partellus。

引言 昆虫的生长和变态严格依赖于含有几丁质的组织和器官中发生的结构变化。几丁质合酶通过 N-乙酰基-D-葡萄糖胺 (GlcNAc) 单体的 β-(1, 4) 糖苷键催化几丁质聚合；昆虫角质层的主要成分。针对这种酶可能是控制害虫同时避免对共存种群产生不利影响的一种有前途的策略。Nikkomycin Z 和 polyoxins 是市售的真菌抑制剂，已知可与昆虫和真菌几丁质合酶的核苷酸结合位点结合。但由于其结构尚不明确，几丁质合酶的结合模式迄今尚未探索。方法 为了解 Chilo partellus 几丁质合酶 (CpCHS) 的结构特征，使用 ROBETTA 网络服务器对 CpCHS 催化域的三维 (3D) 结构进行建模。所获得的模型用于使用 Schrödinger Suite-Maestro v9.2 通过分子对接方法研究其底物尿苷二磷酸-N-乙酰基-D-葡萄糖胺 (UDP-GlcNAc) 和抑制剂（尼可霉素 Z 和多辛）的结合模式. 通过使用 GROMACS v5.1.2 进行分子动力学 (MD) 模拟，进一步研究了对接复合物的相互作用稳定性。结果 我们的研究强调了 Walker-B 环中存在的 CHS 残基和供体结合基序与底物 (UDP-GlcNAc) 以及 GEDR 基序与受体 (GlcNAc) 所产生的各种相互作用的重要性。此外，还探讨了 QRRRW 基序在形成几丁质聚合物时的相互作用。我们观察到抑制剂与这些基序表现出良好的结合亲和力，这由它们的对接和结合亲和力得分表明。结论 体外分析表明，尼可霉素Z在2.5 μg.L-1浓度下对几丁质合酶活性有较高的抑制作用。我们的研究提供了对几丁质合酶的关键相互作用的见解，同时设计了针对害虫的抑制剂。