Journal of Molecular Recognition最新文献

Leucyl-tRNA synthetase (LeuRS) is clinically validated molecular target for antibiotic development. Recently, we have reported several classes of small-molecular inhibitors targeting aminoacyl-adenylate binding site of Mycobacterium tuberculosis LeuRS with antibacterial activity. In this work, we performed in silico site-directed mutagenesis of M. tuberculosis LeuRS synthetic site in order to identify the most critical amino acid residues for the interaction with substrate and prove binding modes of inhibitors. We carried out 20-ns molecular dynamics (MD) simulations and used umbrella sampling (US) method for the calculation of the binding free energy (ΔGb) of leucyl-adenylate with wild-type and mutated forms of LeuRS. According to molecular modeling results, it was found that His89, Tyr93, and Glu660 are essential amino acid residues both for aminoacyl-adenylate affinity and hydrogen bond formation. We have selected His89 for experimental site-directed mutagenesis since according to our previous molecular docking results this amino acid residue was predicted to be important for inhibitor interaction in adenine-binding region. We obtained recombinant mutant M. tuberculosis LeuRS H89A. Using aminoacylation assay we have found that the mutation of His89 to Ala in the active site of M. tuberculosis LeuRS results in significant decrease of inhibitory activity for compounds belonging to three different chemical classes-3-phenyl-5-(1-phenyl-1H-[1,2,3]triazol-4-yl)-[1,2,4]oxadiazoles, N-benzylidene-N'-thiazol-2-yl-hydrazines, and 1-oxo-1H-isothiochromene-3-carboxylic acid (4-phenyl-thiazol-2-yl)-amide derivatives. Therefore, the interaction with His89 should be taken into account during further M. tuberculosis LeuRS inhibitors development and optimization.

Glioblastoma multiforme (GBM) presents a significant challenge in neuro-oncology due to its aggressive behavior and self-renewal capacity. Circular RNAs (circRNAs), a subset of non-coding RNAs (ncRNAs) generated through mRNA back-splicing, are gaining attention as potential targets for GBM research. In our study, we sought to explore the functional role of circMMP9 (circular form of matrix metalloproteinase-9) as a promising therapeutic target for GBM through bioinformatic predictions and human data analysis. Our results suggest that circMMP9 functions as a sponge for miR-149 and miR-542, both upregulated in GBM based on microarray data. Kaplan-Meier analysis indicated that reduced levels of miR-149 and miR-542 correlate with worse survival outcomes in GBM, suggesting their role as tumor suppressors. Importantly, miR-149 has been demonstrated to inhibit the expression of BIRC5 (baculoviral inhibitor of apoptosis repeat-containing 5 or survivin), a significant promoter of proliferation in GBM. BIRC5 is not only upregulated in GBM but also in various other cancers, including neuroblastoma and other brain cancers. Our protein-protein interaction analysis highlights the significance of BIRC5 as a central hub gene in GBM. CircMMP9 seems to influence this complex relationship by suppressing miR-149 and miR-542, despite their increased expression in GBM. Additionally, we found that circMMP9 directly interacts with heterogeneous nuclear ribonucleoproteins C and A1 (hnRNPC and A1), although not within their protein-binding domains. This suggests that hnRNPC/A1 may play a role in transporting circMMP9. Moreover, RNA-seq data from GBM patient samples confirmed the increased expression of BIRC5, PIK3CB, and hnRNPC/A1, further emphasizing the potential therapeutic significance of circMMP9 in GBM. In this study, we propose for the first time a new epigenetic regulatory role for circMMP9, highlighting a novel aspect of its oncogenic function. circMMP9 may regulate BIRC5 expression in GBM by sponging miR-149 and miR-542. BIRC5, in turn, suppresses apoptosis and enhances proliferation in GBM. Nonetheless, more extensive studies are advised to delve deeper into the roles of circMMP9, especially in the context of glioma.

The human papillomavirus (HPV) 33 is a high-risk strain that causes lesions with potential cancerous outcomes. Its E2 protein regulates the viral protein transcription and life cycle maintenance. The DNA binding domain (DBD) of the E2 protein plays a crucial role in the viral life cycle. The DBD region of the E2 protein is particularly interesting for targeting and finding potential inhibitors to inhibit its function or dimerization. Given the limited research on HPV 33 and its proteins, the present work delved into the interaction of two natural polyphenolic compounds, resveratrol, and baicalein, with the E2 DBD of HPV 33 using biophysical and in silico studies. Fluorescence studies of the E2 DBD-polyphenol complexes showed fluorescence quenching with a binding constant of the order of 10⁶ M^-1. Circular dichroism data reveal conformational changes upon binding with the polyphenols, possibly due to distinct binding sites of the E2 DBD. Differential scanning calorimetry exhibited higher melting temperatures for the two complexes than alone DBD, suggesting the complexes' stability. ITC experiment suggested favorable binding reactions with k_d values in the micromolar range. Molecular docking and dynamic simulation studies revealed that the resveratrol binds to the helical region and baicalein near the central dimeric interface of E2 DBD with a good binding affinity, forming a stable protein-ligand complex during the run of 100 ns simulation. Therefore, the current study identifies both polyphenolic compounds as promising candidates for potential antiviral drug development.

The Sec61 translocon mediates the translocation of numerous, newly synthesized precursor proteins into the lumen of the endoplasmic reticulum or their integration into its membrane. Recently, structural biology revealed conformations of idle or substrate-engaged Sec61, and likewise its interactions with the accessory membrane proteins Sec62, Sec63, and TRAP, respectively. Several natural and synthetic small molecules have been shown to block Sec61-mediated protein translocation. Since this is a key step in protein biogenesis, broad inhibition is generally cytotoxic, which may be problematic for a putative drug target. Interestingly, several compounds exhibit client-selective modes of action, such that only translocation of certain precursor proteins was affected. Here, we discuss recent advances of structural biology, molecular modelling, and molecular screening that aim to use Sec61 as feasible drug target.

Due to its intricate molecular and structural characteristics, vascular endothelial growth factor receptor 2 (VEGFR-2) is essential for the development of new blood vessels in various pathological processes and conditions, especially in cancers. VEGFR-2 inhibitors have demonstrated significant anticancer effects by blocking many signaling pathways linked to tumor growth, metastasis, and angiogenesis. Several small compounds, including the well-tolerated sunitinib and sorafenib, have been approved as VEGFR-2 inhibitors. However, the widespread side effects linked to these VEGFR-2 inhibitors-hypertension, epistaxis, proteinuria, and upper respiratory infection-motivate researchers to search for new VEGFR-2 inhibitors with better pharmacokinetic profiles. The key molecular interactions required for the interaction of the small molecules with the protein target to produce the desired pharmacological effects are identified using computer-aided drug design (CADD) methods such as pharmacophore and QSAR modeling, structure-based virtual screening, molecular docking, molecular dynamics (MD) simulation coupled with MM/PB(GB)SA, and other computational strategies. This review discusses the applications of these methods for VEGFR-2 inhibitor design. Future VEGFR-2 inhibitor designs may be influenced by this review, which focuses on the current trends of using multiple screening layers to design better inhibitors.

The monoclonal IgE antibody SPE-7 was originally raised against a 2,4-dinitrophenyl (DNP) target. Through its ability to adopt multiple conformations, the antibody is capable of binding to a diverse range of small haptens and large proteins. The present study examines a dataset of experimentally determined crystal structures of the SPE-7 antibody to gain insight into the mechanisms that contribute to its multispecificity. With the emergence of more and more therapeutic antibodies against a huge repertoire of different targets, our research could be of great interest for future drug development. We are able to discriminate between the different paratope-binding states in the conformational ensembles obtained by enhanced sampling molecular dynamics simulations, and to calculate their transition timescales and state probabilities. Furthermore, we describe the key residues responsible for discriminating between the different binding capacities and identify a tryptophan in a central position of the CDR L3 loop as the residue of greatest interest. The overall dynamics of the paratope appear to be mainly influenced by the CDR L3 and CDR L1 loops.

After the recent double revolutions in structural biology, which include the use of direct detectors for cryo-electron microscopy resulting in a significant improvement in the expected resolution of large macromolecule structures, and the advent of AlphaFold which allows for near-accurate prediction of any protein structures, the field of structural biology is now pursuing more ambitious targets, including several MDa assemblies. But complex target systems cannot be tackled using a single biophysical technique. The field of integrative structural biology has emerged as a global solution. The aim is to integrate data from multiple complementary techniques to produce a final three-dimensional model that cannot be obtained from any single technique. The absence of atomic force microscopy data from integrative structural biology platforms is not necessarily due to its nm resolution, as opposed to Å resolution for x-ray crystallography, nuclear magnetic resonance, or electron microscopy. Rather a significant issue was that the AFM topographic data lacked interpretability. Fortunately, with the introduction of the AFM-Assembly pipeline and other similar tools, it is now possible to integrate AFM topographic data into integrative modeling platforms. The advantages of single molecule techniques, such as AFM, include the ability to confirm experimentally any assembled molecular models or to produce alternative conformations that mimic the inherent flexibility of large proteins or complexes. The review begins with a brief overview of the historical developments of AFM data in structural biology, followed by an examination of the strengths and limitations of AFM imaging, which have hindered its integration into modern modeling platforms. This review discusses the correction and improvement of AFM topographic images, as well as the principles behind the AFM-Assembly pipeline. It also presents and discusses a series of challenges that need to be addressed in order to improve the incorporation of AFM data into integrative modeling platform.

Drug molecules exist as complexed with serum proteins such as human serum albumin (HSA) and/or unbound free form in the blood circulation. Drugs can be effective only when they are free. Thus, it is important to understand aspects that are important for interaction between drugs and interacting proteins. In this study, interactions among 2990 FDA approved drugs and HSA were computational analyzed to unravel principles that are critical for drug-HSA interactions. Docking results showed that drugs have higher affinity toward cavity-1 (C1) than cavity-2 (C2). A total of 1131 drug molecules have docking score greater than 60 while 768 molecules have docking score greater than 60 when they are docked in C2. In addition, three solvent channels have potential to direct solvent to C1 cavity while C2 does not have any effective channel. The post MD analyses demonstrated that drugs are making polar interactions with basic amino acids in the binding cavities. Verbscoside and ceftazidime both have stable low RMSD values throughout MD simulation with 2 Å on average in C1 cavity. The ligand RMSD shows less stability for verbscoside, which is around 4 Å when it is in complex with HSA in C1. The individual contribution of the residues K192, K196, R215, and R254 to ceftazidime are −1.92 ± 0.18, −3.09 ± 0.09, −2.17 ± 0.17, and − 2.32 ± 0.098, respectively. These residues contribute the binding energy of the verbscoside by −6.06 ± 0.08, −2.10 ± 0.06, and − 1.57 ± 0.03 kcal/mol individually in C1 cavity. C2 is making polar interactions with drug via R469, K472, and K488 residues and their contribution to the two drugs are −3.13 ± 0.21 kcal/mol for R469, −1.94 ± 0.18 kcal/mol for K472, and −1.96 ± 0.11 kcal/mol for K488 to total binding energy of ceftazidime. The binding energy of verbscoside is 57.17 ± 7.00 kcal/mol and Arg-407 has the highest contribution this bind energy individually with −4.29 ± 0.12 kcal/mol. Drugs with hydrogen bond donor/acceptor chemical adducts such as verbscoside involve higher hydrogen bond formation in C1 pocket. Ceftazidime makes interaction with HSA toward hydrophobic residues, L384, L404, L487, and L488 in the C2 cavity.