scholarly journals Molecular Mechanism of DAPD/DXG against Zidovudine- and Lamivudine- Drug Resistant Mutants: A Molecular Modelling Approach

2002 ◽  
Vol 13 (2) ◽  
pp. 115-128 ◽  
Author(s):  
Youhoon Chong ◽  
Katyna Borroto-Esoda ◽  
Phillip A Furman ◽  
Raymond F Schinazi ◽  
Chung K Chu
Keyword(s):  
Drug Resistance ◽  
Amino Acid ◽  
Antiviral Activity ◽  
Molecular Mechanism ◽  
Binding Affinity ◽  
Molecular Modelling ◽  
Enzyme Inhibitor ◽  
Drug Resistant ◽  
Amino Acid Residues ◽  
Resistant Mutants

In order to understand molecular mechanism of antiviral drug resistance of HIV-1 reverse transcriptase (RT) as well as potent antiviral activity of 2,6-diaminopurine dioxolane (DAPD) [prodrug of (–)-β-D-dioxolane guanine (DXG)] against drug-resistant RTs, molecular modelling studies of three structurally distinct nucleoside RT inhibitor (NRTI)-triphosphates (TP) [zidovudine (AZT)-TP, lamivudine (3TC)-TP and DXG-TP] complexed with the wild-type (WT) and mutated RT were conducted. The computational analyses indicated that the antiviral activity and the calculated relative binding energy of the RT inhibitor triphosphates can be correlated, and the minimized structures gave information on the molecular mechanism of drug resistance conferred by mutations. The interactions between the NRTI-TP and adjacent amino acid residues (Lys65, Lys70, Arg72, Tyr115 and/or Gln151) played important roles in stabilizing the enzyme—inhibitor complex. Particularly, Arg72 was found to stabilize the dioxolane and oxathiolane sugar moiety through hydrogen bonding, which was responsible for favourable binding affinity of DXG-TP to AZT- as well as 3TC-resistant mutants. The conformational changes in these amino acid residues caused by mutation always affected the changes in the tertiary structures of enzyme-inhibitor complexes through either closing or opening the gap between the fingers and palm domains. The enzyme-inhibitor complexes with good binding affinity showed tight binding modes by closing the gap between the two domains, whereas weak inhibitors gave open and loose complexes.

Hybrid QM/MM free energy evaluation of drug-resistant mutational effect on binding of an inhibitor Indinavir to HIV protease

2021 ◽  
Author(s):  
Masahiko Taguchi ◽  
Ryo Oyama ◽  
Masahiro Kaneso ◽  
Shigehiko Hayashi
Keyword(s):  
Drug Resistance ◽  
Free Energy ◽  
Ligand Binding ◽  
Transition State ◽  
Molecular Mechanism ◽  
Binding Affinity ◽  
Free Energy Calculations ◽  
Drug Resistant ◽  
Transition State Analog ◽  
Hiv 1

Human immunodeficiency virus 1 (HIV-1) protease is a homo-dimeric aspartic protease essential for replication of HIV. The HIV-1 protease is a target protein in drug discovery for antiretroviral therapy, and various inhibitor molecules of transition state analog were developed. However, serious drug-resistant mutants have emerged. For understanding molecular mechanism of the drug-resistance, accurate examination of the impacts of the mutations on ligand binding as well as enzymatic activity is necessary. Here, we present a molecular simulation study on the ligand binding of Indinavir, a potent transition state analog inhibitor, to the native protein and a V82T/I84V drug-resistant mutant of HIV-1 protease. We employed a hybrid ab initio quantum mechanical/molecular mechanical (QM/MM) free energy optimization technique which combines highly accurate QM description of the ligand molecule and its interaction with statistically ample conformational sampling of MM protein environment by long-time molecular dynamics simulations. Through free energy calculations of protonation states of catalytic groups at the binding pocket and of ligand binding affinity changes upon the mutations, we successfully reproduced the experimentally observed significant reduction of the binding affinity upon the drug-resistant mutations and elucidated the underlying molecular mechanism. The present study opens the way for understanding the molecular mechanism of drug-resistance through direct quantitative comparison of ligand binding and enzymatic reaction with the same accuracy.

scholarly journals Hybrid QM/MM free energy evaluation of drug-resistant mutational effect on binding of an inhibitor Indinavir to HIV protease

2021 ◽  
Author(s):  
Masahiko Taguchi ◽  
Ryo Oyama ◽  
Masahiro Kaneso ◽  
Shigehiko Hayashi
Keyword(s):  
Drug Resistance ◽  
Free Energy ◽  
Ligand Binding ◽  
Transition State ◽  
Molecular Mechanism ◽  
Binding Affinity ◽  
Free Energy Calculations ◽  
Drug Resistant ◽  
Transition State Analog ◽  
Hiv 1

Human immunodeficiency virus 1 (HIV-1) protease is a homo-dimeric aspartic protease essential for replication of HIV. The HIV-1 protease is a target protein in drug discovery for antiretroviral therapy, and various inhibitor molecules of transition state analog were developed. However, serious drug-resistant mutants have emerged. For understanding molecular mechanism of the drug-resistance, accurate examination of the impacts of the mutations on ligand binding as well as enzymatic activity is necessary. Here, we present a molecular simulation study on the ligand binding of Indinavir, a potent transition state analog inhibitor, to the native protein and a V82T/I84V drug-resistant mutant of HIV-1 protease. We employed a hybrid ab initio quantum mechanical/molecular mechanical (QM/MM) free energy optimization technique which combines highly accurate QM description of the ligand molecule and its interaction with statistically ample conformational sampling of MM protein environment by long-time molecular dynamics simulations. Through free energy calculations of protonation states of catalytic groups at the binding pocket and of ligand binding affinity changes upon the mutations, we successfully reproduced the experimentally observed significant reduction of the binding affinity upon the drug-resistant mutations and elucidated the underlying molecular mechanism. The present study opens the way for understanding the molecular mechanism of drug-resistance through direct quantitative comparison of ligand binding and enzymatic reaction with the same accuracy.

scholarly journals The Differential Binding Affinities of the Luteinizing Hormone (LH)/Choriogonadotropin Receptor for LH and Choriogonadotropin Are Dictated by Different Extracellular Domain Residues

2005 ◽  
Vol 19 (5) ◽  
pp. 1263-1276 ◽  
Author(s):  
Colette Galet ◽  
Mario Ascoli
Keyword(s):  
Amino Acid ◽  
Ligand Binding ◽  
Binding Affinity ◽  
Extracellular Domain ◽  
Binding Affinities ◽  
Amino Acid Residues ◽  
Identify Amino Acid ◽  
Β Sheets ◽  
Leucine Rich Repeats ◽  
High Degree

Abstract The high degree of amino acid sequence homology and the divergent ligand binding affinities of the rat (r) and human (h) LH receptors (LHRs) allowed us to identify amino acid residues of their extracellular domain that are responsible for the different binding affinities of bovine (b) and hLH, and human choriogonadotropin (hCG) to the hLHR and rLHR. Because of the proposed importance of the β-sheets of the leucine-rich repeats (LRRs) of the extracellular domain of the LHR on hormone binding, we examined 10 divergent residues present in these regions by analyzing two complementary sets of mutants in which hLHR residues were substituted with the corresponding rLHR residues and vice versa. These experiments resulted in the identification of a single residue (a Ile or Ser in the C-terminal end of LRR2 of the hLHR or rLHR, respectively) that is important for hLH binding affinity. Surprisingly, however, this residue does not affect hCG or for bLH binding affinity. In fact, the results obtained with bLH and hCG show that several of the divergent residues in the β-sheets of LRR1–9 affect bLH binding affinity, but none of them affect hCG binding affinity. Importantly, our results also emphasize the involvement of residues outside of the β-sheets of the LRRs of the LHR in ligand binding affinity. This finding has to be considered in future models of the interaction of LH/CG with the LHR.

scholarly journals Critical Amino Acid Residues Determine the Binding Affinity and the Ca2+ Release Efficacy of Maurocalcine in Skeletal Muscle Cells

2003 ◽  
Vol 278 (39) ◽  
pp. 37822-37831 ◽  
Author(s):  
Eric Estève ◽  
Sophia Smida-Rezgui ◽  
Sandor Sarkozi ◽  
Csaba Szegedi ◽  
Imed Regaya ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Amino Acid ◽  
Binding Affinity ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Amino Acid Residues ◽  
Critical Amino Acid

scholarly journals The Potential Role of 6-gingerol and 6-shogaol as ACE Inhibitors in Silico Study

2020 ◽  
Vol 8 (2) ◽  
pp. 210
Author(s):  
Yohanes Bare ◽  
Maria Helvina ◽  
Gabriella Chandrakirana Krisnamurti ◽  
Mansur S
Keyword(s):  
Amino Acid ◽  
Angiotensin Converting Enzyme ◽  
Binding Site ◽  
Potential Role ◽  
Enzyme Inhibitor ◽  
Renin Angiotensin System ◽  
Data Bank ◽  
Amino Acid Residues ◽  
Converting Enzyme

Hypertension has become the third highest cause of death in Indonesia. The condition is correlated with angiotensin-converting enzyme (ACE), and possibly managed with the use of drugs. In addition, some natural compounds, including 6-shogaol and 6-gingerol from ginger, are used to decrease blood pressure. However, the mechanism and binding site of these compounds to ACE protein is currently unclear. This study, therefore, aims to investigate the potential role of these compounds as an angiotensin-converting enzyme inhibitor. The ACE protein was downloaded from Protein Data Bank (PDB) database with the ID: 3bkk, while the 6-shogaol (CID: 5281794) and 6-gingerol (CID: 44559528) ligands were obtained from the PubChem database. Meanwhile, molecular docking was established using HEX 8.0.0 software. The analysis examined the amino acid residues and the bonds formed from these interactions. According to the results, fourteen amino acid residues were formed by the interaction between 6-shogaol and ACE, while the interaction between 6-gingerol and ACE formed eight amino acids. Also, thirteen amino acid residues in the novelty binding site of ACE were discovered to be blocked by the ligands from ginger. Therefore, the compounds have potential roles as inhibitors, and this possibly helps to prevent regulation of the renin-angiotensin system. These interactions also formed hydrogen bonds, as well as electrostatic, unfavorable, and hydrophobic sites, making the binding stronger than others. 

scholarly journals Two Lytic Bacteriophages That Depend on theEscherichia coliMulti-Drug Efflux GenetolCand Differentially Affect Bacterial Growth and Selection

2018 ◽  
Author(s):  
Alita R. Burmeister ◽  
Rose G. Bender ◽  
Abigail Fortier ◽  
Adam J. Lessing ◽  
Benjamin K. Chan ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Antibiotic Resistance ◽  
Resistance Gene ◽  
Bacterial Growth ◽  
Bacterial Pathogens ◽  
Antibiotic Resistance Gene ◽  
Resistant Bacteria ◽  
Drug Efflux ◽  
Drug Resistant ◽  
Resistant Mutants

AbstractBacterial pathogens are increasingly evolving drug resistance under natural selection from antibiotics in medicine, agriculture, and nature. Meanwhile, bacteria ubiquitously encounter bacteriophages and can rapidly evolve phage resistance. However, the role of phages in interacting with drug-resistant and drug-sensitive bacteria remains unclear. To gain insight into such relationships, we screened for and characterized phages that rely on the multi-drug efflux pump genetolC. First, we screened a collection of 33 environmental and commercialEscherichia coliphages for their ability to infect cells that lackedtolC. Our screen revealed two phages that had reduced efficiency of plating (EOP) on thetolCknockout compared to wild type. We further characterized these phages with bacterial growth curves, transmission electron microscopy, and analysis of phage-resistant mutants. Phage U136B is a curly-tailed virus in familySiphoviridaewith no ability to infect atolCknockout, suggesting TolC is the U136B receptor. Phage 132 is a contractile-tailed virus in familyMyoviridaewith reduced EOP on cells lackingompFand its positive regulatorstolCandompR. U136B and 132 differentially effect bacterial growth and lysis, and U136B-resistant mutants contain mutations of thetolCgene. Together, these results show that thetolCgene involved in drug resistance can modify bacteria-phage interactions in multiple ways, altering bacterial lysis and selection. These new phages offer utility for studying evolution, tradeoffs, and infection mechanisms.ImportanceBacteria face strong selection by antibiotics in medicine and agriculture, resulting in increasing levels of drug resistance among bacterial pathogens. Slowing this process will require an understanding of the environmental contexts in which drug resistance evolutionarily increases or decreases. In this study, we investigate two newly-isolated bacteriophages that rely on a bacterial antibiotic resistance gene. These bacteriophages vary in their interactions with drug-resistant bacteria, with one of the phages selecting for phage-resistant mutants that have mutations in the antibiotic resistance gene. Further study of these new phages will be useful to understanding evolutionary tradeoffs and how phages might be applied in natural settings to reverse the problem of drug resistance.

scholarly journals Charge reversal of ammodytoxin A, a phospholipase A2-toxin, does not abolish its neurotoxicity

2000 ◽  
Vol 352 (2) ◽  
pp. 251-255 ◽  
Author(s):  
Petra PRIJATELJ ◽  
Alenka ČOPIČ ◽  
Igor KRIŽAJ ◽  
Franc GUBENŠEK ◽  
Jože PUNGERČAR
Keyword(s):  
Amino Acid ◽  
Phospholipase A2 ◽  
Binding Affinity ◽  
Positive Charge ◽  
Basic Amino Acid ◽  
Terminal Region ◽  
Single Site ◽  
Amino Acid Residues ◽  
Multiple Site ◽  
Charge Reversal

The positive charge concentrated at the C-terminal region of ammodytoxin (Atx) A, which is involved in presynaptic toxicity, has been reversed. A six-site mutant of AtxA (K108N/K111N/K127T/K128E/E129T/K132E, where K108N = Lys108 → Asn etc.) was prepared, in which five out of seven C-terminal basic amino acid residues were substituted with neutral or acidic ones. The mutant was approximately 30-fold less lethal, but still neurotoxic. Consistent with this, its binding affinity for the neuronal receptors decreased by only a factor of five. Additionally, a single-site mutant of AtxA was prepared, with substitution at only one position (K127T) out of six mutated in the six-site mutant. Its toxicity indicated that most, if not all, of the six mutated residues partially contribute to the decreased lethality of the multiple-site mutant.

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