Background: Enterococcus faecalis (Ef) infections are becoming dreadfully common in hospital environments. Infections caused by Ef are difficult to treat because of its acquired resistance to different class of antibiotics, making it a multidrug resistant bacteria. Key pathogenic factor of Ef includes its ability to form biofilm on the surface of diagnostic and other medical devices. Sortase A (SrtA) is a cysteine transpeptidase which plays a pivotal role in the formation of biofilm in Ef, hence, it is considered as an important enzyme for the pathogenesis of Ef. Thus, inhibition of (SrtA) will affect biofilm formation, which will reduce its virulence and eventually Ef infection will be abridged.

Objective: To find potential inhibitors of Enterococcus faecalis Sortase A (EfSrtA) through insilico and in-vitro methods.

Methods: Gene coding for EfSrtA was cloned, expressed and purified. Three-dimensional model of EfSrtA was created using Swiss-Model workspace. In-silico docking studies using Autodock vina and molecular dynamics simulations of the modelled structures using Gromacs platform were performed to explore potential lead compounds against EfSrtA. In-vitro binding experiments using spectrofluorometric technique was carried out to confirm and validate the study.

Results: In-silico docking and in-vitro binding experiments revealed that curcumin, berberine and myricetin bound to EfSrtA at nanomolar concentrations with high affinity.

Conclusion: This is a first structural report of EfSrtA with curcumin, berberine and myricetin. Taking in account the herbal nature of these compounds, the use of these compounds as inhibitors will be advantageous. This study validated curcumin, berberine and myricetin as potential inhibitors of EfSrtA.

背景：粪肠球菌（Ef）感染在医院环境中变得越来越普遍。Ef引起的感染难以治疗，因为它对不同种类的抗生素具有抗药性，使其成为具有多重耐药性的细菌。Ef的主要致病因素包括其在诊断和其他医疗设备表面形成生物膜的能力。分选酶A（SrtA）是半胱氨酸转肽酶，在Ef中生物膜的形成中起关键作用，因此，它被认为是Ef发病的重要酶。因此，对（SrtA）的抑制将影响生物膜的形成，这将降低其毒力，并最终减少Ef感染。

目的：通过计算机和体外方法寻找粪肠球菌分选酶A（EfSrtA）的潜在抑制剂。

方法：克隆，表达和纯化编码EfSrtA的基因。EfSrtA的三维模型是使用Swiss-Model工作区创建的。进行了使用Autodock芯片的硅对接研究，并使用Gromacs平台对建模结构进行了分子动力学模拟，以探索针对EfSrtA的潜在先导化合物。使用荧光分光光度技术进行了体外结合实验，以证实和验证该研究。

结果：计算机对接和体外结合实验表明，姜黄素，小ber碱和杨梅素在纳摩尔浓度下以高亲和力与EfSrtA结合。

结论：这是EfSrtA与姜黄素，小ber碱和杨梅素的第一份结构报告。考虑到这些化合物的草药性质，使用这些化合物作为抑制剂将是有利的。这项研究证实姜黄素，小ber碱和杨梅素是EfSrtA的潜在抑制剂。