Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, The University of Western Australia, Perth, Western Australia, 6008, Australia.
Wesfarmers Centre for Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Nedlands, Western Australia, 6008, Australia.
J Antimicrob Chemother. 2022 May 29;77(6):1625-1634. doi: 10.1093/jac/dkac065.
The macrophage infectivity potentiator (Mip) protein, which belongs to the immunophilin superfamily, is a peptidyl-prolyl cis/trans isomerase (PPIase) enzyme. Mip has been shown to be important for virulence in a wide range of pathogenic microorganisms. It has previously been demonstrated that small-molecule compounds designed to target Mip from the Gram-negative bacterium Burkholderia pseudomallei bind at the site of enzymatic activity of the protein, inhibiting the in vitro activity of Mip.
In this study, co-crystallography experiments with recombinant B. pseudomallei Mip (BpMip) protein and Mip inhibitors, biochemical analysis and computational modelling were used to predict the efficacy of lead compounds for broad-spectrum activity against other pathogens.
Binding activity of three lead compounds targeting BpMip was verified using surface plasmon resonance spectroscopy. The determination of crystal structures of BpMip in complex with these compounds, together with molecular modelling and in vitro assays, was used to determine whether the compounds have broad-spectrum antimicrobial activity against pathogens.
Of the three lead small-molecule compounds, two were effective in inhibiting the PPIase activity of Mip proteins from Neisseria meningitidis, Klebsiella pneumoniae and Leishmania major. The compounds also reduced the intracellular burden of these pathogens using in vitro cell infection assays.
These results indicate that Mip is a novel antivirulence target that can be inhibited using small-molecule compounds that prove to be promising broad-spectrum drug candidates in vitro. Further optimization of compounds is required for in vivo evaluation and future clinical applications.
巨噬细胞感染增强因子（Mip）蛋白属于免疫亲和素超家族，是一种肽基脯氨酰顺/反式异构酶（PPIase）酶。Mip 已被证明在广泛的致病微生物的毒力中非常重要。先前已经证明，针对革兰氏阴性菌伯克霍尔德菌属假单胞菌的 Mip 设计的小分子化合物结合在蛋白质的酶活性部位，抑制 Mip 的体外活性。
在这项研究中，使用重组 B. pseudomallei Mip（BpMip）蛋白和 Mip 抑制剂的共结晶实验、生化分析和计算建模，预测针对其他病原体具有广谱活性的先导化合物的疗效。
使用表面等离子体共振光谱法验证了三种针对 BpMip 的先导化合物的结合活性。通过测定与这些化合物复合的 BpMip 的晶体结构，以及分子建模和体外测定，确定这些化合物是否对病原体具有广谱抗菌活性。
在这三种先导小分子化合物中，有两种有效抑制了脑膜炎奈瑟菌、肺炎克雷伯菌和利什曼原虫 Mip 蛋白的 PPIase 活性。这些化合物还通过体外细胞感染实验降低了这些病原体的细胞内负担。
这些结果表明，Mip 是一种新型的抗病毒靶点，可以使用小分子化合物进行抑制，这些化合物在体外被证明是有前途的广谱药物候选物。需要进一步优化化合物，以进行体内评估和未来的临床应用。
