Novel inhibitor discovery and the conformational analysis of inhibitors of listeriolysin O via protein-ligand modeling.

Jianfeng Wang,Xuan Zhou,Xiaodi Niu,Bing Zhang,Shui Liu,Xuming Deng,Gen Li

doi:10.1038/srep08864

Abstract

Increasing bacterial resistance to available antibiotics makes the discovery of novel efficacious antibacterial agents a priority. A previous report showed that listeriolysin O (LLO) is a critical virulence factor and suggested that it is a target for developing anti-virulence drugs against Listeria monocytogenes infections. In this study, we report the discovery of LLO natural compound inhibitors with differential activity by using hemolysis assay. The mechanism of action of the inhibitors was consistent with that of fisetin, a natural flavonoid without antimicrobial activity, which we showed in our previous report via molecular simulation. Furthermore, a substantial increase in anti-hemolytic activity was observed when the single bond (C1-C2) was replaced by a double bond (C1-C2) in the inhibitor molecule. This change was based on the decomposition of the ligand-residue interaction, which indicated that the double bond (C1-C2) in the inhibitors was required for their inhibition of LLO. The current MD simulation work provides insights into the mechanism by which the compounds inhibit LLO at the atomic level and will be useful for the development of new, selective LLO inhibitors.

Highlights

Key Laboratory of Zoonosis, Ministry of Education, Department of Food Quality and Safety, College of Veterinary Medicine, Jilin University, Changchun, China
A previous report showed that listeriolysin O (LLO) is a critical virulence factor and suggested that it is a target for developing anti-virulence drugs against Listeria monocytogenes infections
We reported that the direct engagement of fisetin to the Loop[2] and Loop 3 of LLO blocks the binding of cholesterol (CHO), an essential structural component of animal cell membranes that is required for the oligomerization of LLO, to LLO

Summary

Introduction

A previous report showed that listeriolysin O (LLO) is a critical virulence factor and suggested that it is a target for developing anti-virulence drugs against Listeria monocytogenes infections. A previous study in our lab demonstrated that fisetin, a natural compound without anti-bacterial activity, inhibits the virulence of L. monocytogenes by attenuating the hemolytic activity of LLO13. We hypothesized that screening natural compound inhibitors for inhibition of LLO could contribute to anti-virulence drug discovery by providing optimal host defense against L. monocytogenes infections. We reported that the direct engagement of fisetin to the Loop[2] and Loop 3 of LLO blocks the binding of cholesterol (CHO), an essential structural component of animal cell membranes that is required for the oligomerization of LLO, to LLO This subsequently reduces the oligomerization of LLO, inhibiting its hemolytic activity. The results from our study suggest that the double bond (C1-C2) is one of the key moieties in the inhibitors of LLO, and the compounds with the double bond (Myr, Mor and Bac) may be more promising candidate for the design of novel and potent inhibitors of LLO

Methods

Results

Conclusion