School of Biotechnology, Jawaharlal Nehru University, New Delhi, 110067, India.
Jamia Hamdard Institute of Molecular Medicine, Jamia Hamdard, New Delhi, 110062, India.
Sci Rep. 2020 Mar 10;10(1):4413. doi: 10.1038/s41598-020-61132-w.
Tuberculosis (TB) is a leading cause of death worldwide and its impact has intensified due to the emergence of multi drug-resistant (MDR) and extensively drug-resistant (XDR) TB strains. Protein phosphorylation plays a vital role in the virulence of Mycobacterium tuberculosis (M.tb) mediated by protein kinases. Protein tyrosine phosphatase A (MptpA) undergoes phosphorylation by a unique tyrosine-specific kinase, protein tyrosine kinase A (PtkA), identified in the M.tb genome. PtkA phosphorylates PtpA on the tyrosine residues at positions 128 and 129, thereby increasing PtpA activity and promoting pathogenicity of MptpA. In the present study, we performed an extensive investigation of the conformational behavior of the intrinsically disordered domain (IDD) of PtkA using replica exchange molecular dynamics simulations. Long-term molecular dynamics (MD) simulations were performed to elucidate the role of IDD on the catalytic activity of kinase core domain (KCD) of PtkA. This was followed by identification of the probable inhibitors of PtkA using drug repurposing to block the PtpA-PtkA interaction. The inhibitory role of IDD on KCD has already been established; however, various analyses conducted in the present study showed that IDD had a greater inhibitory effect on the catalytic activity of KCD in the presence of the drugs esculin and inosine pranobex. The binding of drugs to PtkA resulted in formation of stable complexes, indicating that these two drugs are potentially useful as inhibitors of M.tb.
结核病（TB）是全球主要死因之一，由于多药耐药（MDR）和广泛耐药（XDR）结核菌株的出现，其影响加剧。蛋白质磷酸化在分枝杆菌（M.tb）介导的毒力中起着至关重要的作用，蛋白激酶参与了该过程。M.tb 基因组中鉴定出一种独特的酪氨酸特异性激酶，即蛋白酪氨酸激酶 A（PtkA），可使蛋白酪氨酸磷酸酶 A（MptpA）发生磷酸化。PtkA 在 MptpA 的酪氨酸残基 128 和 129 位上进行磷酸化，从而增加 MptpA 的活性并促进其致病性。在本研究中，我们使用副本交换分子动力学模拟对 PtkA 的固有无序结构域（IDD）的构象行为进行了广泛研究。进行了长期的分子动力学（MD）模拟，以阐明 IDD 在 PtkA 的激酶核心结构域（KCD）的催化活性中的作用。随后，使用药物再利用来阻断 PtpA-PtkA 相互作用，鉴定了 PtkA 的可能抑制剂。已经证实 IDD 对 KCD 的抑制作用；然而，本研究中的各种分析表明，在药物秦皮乙素和肌苷普拉诺昔布存在的情况下，ID 在 KCD 的催化活性上具有更大的抑制作用。药物与 PtkA 的结合导致形成稳定的复合物，这表明这两种药物可能是 M.tb 的潜在抑制剂。
