In‐Cell NMR Spectroscopy of Intrinsically Disordered Proteins

This review summarizes the results of in‐cell Nuclear Magnetic Resonance, NMR, spectroscopic investigations of the eukaryotic and prokaryotic intrinsically disordered proteins, IDPs: α‐synuclein, prokaryotic ubiquitin‐like protein, Pup, tubulin‐related neuronal protein, Tau, phenylalanyl‐glycyl‐repeat‐rich nucleoporins, FG Nups, and the negative regulator of flagellin synthesis, FlgM. The results show that the cellular behavior of IDPs may differ significantly from that observed in the test tube.     

Molecular dynamics simulation and binding free energy studies of novel leads belonging to the benzofuran class inhibitors of Mycobacterium tuberculosis Polyketide Synthase 13

In this work, the binding mechanism of new Polyketide Synthase 13 (Pks13) inhibitors has been studied through molecular dynamics simulation and free energy calculations. The drug Tam1 and its analogs, belonging to the benzofuran class, were submitted to 100 ns simulations, and according to the results obtained for root mean square deviation, all the simulations converged from approximately 30 ns. For the analysis of backbone flotation, the root mean square fluctuations were plotted for the Cα atoms; analysis revealed that the greatest fluctuation occurred in the residues that are part of the protein lid domain. The binding free energy value (ΔG_bind) obtained for the Tam16 lead molecule was of ?51.43 kcal/mol. When comparing this result with the ΔG_bind values for the remaining analogs, the drug Tam16 was found to be the highest ranked: this result is in agreement with the experimental results obtained by Aggarwal and collaborators, where it was verified that the IC₅₀ for Tam16 is the smallest necessary to inhibit the Pks13 (IC₅₀ = 0.19 μM). The energy decomposition analysis suggested that the residues which most interact with inhibitors are: Ser1636, Tyr1637, Asn1640, Ala1667, Phe1670, and Tyr1674, from which the greatest energy contribution to Phe1670 was particularly notable. For the lead molecule Tam16, a hydrogen bond with the hydroxyl of the phenol not observed in the other analogs induced a more stable molecular structure. Aggarwal and colleagues reported this hydrogen bonding as being responsible for the stability of the molecule, optimizing its physic-chemical, toxicological, and pharmacokinetic properties.     

In silico discovery of potential drug molecules to improve the treatment of isoniazid-resistant Mycobacterium tuberculosis

The emergence of multidrug-resistant Mycobacterium tuberculosis (M.tb) has become one of the major hurdles in the treatment of tuberculosis (TB). Drug-resistant M.tb has evolved with various strategies to avoid killing by the anti-tubercular drugs. Thus, there is a rising need to develop effective anti-TB drugs to improve the treatment of these strains. Traditional drug design approach has earned little success due to time and the cost involved in the process of development of anti-infective drugs. Numerous reports have demonstrated that several mutations in the drug target sites cause emergence of drug-resistant M.tb strains. In this study, we performed computational mutational analysis of M.tb inhA, fabD, and ahpC genes, which are the primary targets for first-line isoniazid (INH) drug. In silico virtual drug screening was performed to identify the potent drugs from a ChEMBL compound library to improve the treatment of INH-resistant M.tb. Further, these compounds were analyzed for their binding efficiency against active drug binding cavity of M.tb wild-type and mutant InhA, FabD and AhpC proteins. The drug efficacy of predicted lead compounds was verified by molecular docking using M.tb wild-type and mutant InhA, FabD and AhpC protein template models. Different in silico and pharmacophore analysis predicted three potent lead compounds with better drug-like properties against both M.tb wild-type and mutant InhA, FabD, and AhpC proteins as compared to INH drug, and thus may be considered as effective drugs for the treatment of INH-resistant M.tb strains. We hypothesize that this work may accelerate drug discovery process for the treatment of drug-resistant TB.

Communicated by Ramaswamy H. Sarma     

Role of two-component regulatory systems in intracellular survival of Mycobacterium tuberculosis

The typical two-component regulatory systems (TCSs), consisting of response regulator and histidine kinase, play a central role in survival of pathogenic bacteria under stress conditions such as nutrient starvation, hypoxia, and nitrosative stress. A total of 11 complete paired two-component regulatory systems have been found in Mycobacterium tuberculosis, including a few isolated kinase and regulatory genes. Increasing evidence has shown that TCSs are closely associated with multiple physiological process like intracellular persistence, pathogenicity, and metabolism. This review gives the two-component signal transduction systems in M. tuberculosis and their signal transduction roles in adaption to the environment.     

结核分枝杆菌毒力因子蛋白酪氨酸磷酸酶PtpA转录调控和分泌机理

结核分枝杆菌感染引起的结核病疫情依然严峻。感染的结核菌可分泌一系列效应分子调控、干扰和逃逸宿主免疫。本文综述蛋白酪氨酸磷酸酶PtpA在结核菌感染中发挥的重要作用:经多条途径抑制宿主天然免疫、细胞凋亡及吞噬体-溶酶体融合、调控宿主能量代谢等逃逸免疫杀伤。作为候选药物靶标,靶向PtpA的抑制剂设计、筛选及药物研发较为迟缓,因为PtpA与宿主蛋白酪氨酸磷酸酶hLMW-PTP具有较高一致性。为了进一步探索靶向该分子的更佳途径,分析了ptpA基因转录及PtpA蛋白分泌方面的研究进展及存在问题,为靶向PtpA的其他途径提供参考。     

Exosomes in tuberculosis: Still terra incognita?

Today, diagnosis, vaccination, and treatment of tuberculosis (TB) remain major clinical challenges. Therefore, an introduction of new diagnostic measures and biomarkers is necessary to improve infection control. The ideal biomarker for TB infection can be defined as a host or pathogen-derived biomolecule, which is potent for identifying infection and determining its clinical stage. Exosomes, defined as cell-derived nanovesicles released into biological fluids, are involved in cell–cell communication and immune modulation. These vesicles have emerged as a new platform for improving the clinical diagnosis and prognosis of different infectious diseases and cancers. The role of these nanovehicles, as alternative biomarkers for the improvement of TB diagnosis and treatment, has been demonstrated in a significant body of literature. In this review, we summarized recent progress in the clinical application of exosome-based biomarkers in TB infection.     

痰涂片标本用于结核分枝杆菌耐药性检测的研究

目的 研究抗酸染色结核分枝杆菌(简称结核杆菌)阳性痰涂片标本直接用于耐药性检测的方法。方法 对18株临床分离培养的结核杆菌用利福平进行药敏试验。分别提取菌株DNA和与之对应的痰涂片标本的菌体DNA,用聚合酶链反应(PcR)扩增ropB基因后进行固相杂交和核酸测序检测结核杆菌的耐药性。结果 18株结核杆菌中有12株对利福平耐药。经PCR扩增的ropB片段与探针杂交后,敏感菌株未发现rpoB基因的突变,自耐药菌株提取的DNA中rpoB突变体的检出率为100％(12／12),痰涂片提取DNA的检出率为91．7％(11／12)。所有耐药菌株DNA与痰涂片DNA核酸测序结果相吻合,都有rpoB基因核心区域碱基突变。结论 抗酸染色痰涂片阳性标本可直接用于检测结核杆菌利福平耐药基因rpoB突变体,是一种值得临床实验室推广使用的耐药菌诊断方法。