Structure and mechanism of the γ-glutamyl-γ-aminobutyrate hydrolase SpuA from Pseudomonas aeruginosa

2021 ◽  
Vol 77 (10) ◽  
pp. 1305-1316
Author(s):  
Yujing Chen ◽  
Haizhu Jia ◽  
Jianyu Zhang ◽  
Yakun Liang ◽  
Ruihua Liu ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Catalytic Mechanism ◽  
Substrate Binding ◽  
Binding Pocket ◽  
Class I ◽  
Polyamine Metabolism ◽  
Binding Assays ◽  
Starting Point ◽  
Family Activity ◽  
Living Organisms

Polyamines are important regulators in all living organisms and are implicated in essential biological processes including cell growth, differentiation and apoptosis. Pseudomonas aeruginosa possesses an spuABCDEFGHI gene cluster that is involved in the metabolism and uptake of two polyamines: spermidine and putrescine. In the proposed γ-glutamylation–putrescine metabolism pathway, SpuA hydrolyzes γ-glutamyl-γ-aminobutyrate (γ-Glu-GABA) to glutamate and γ-aminobutyric acid (GABA). In this study, crystal structures of P. aeruginosa SpuA are reported, confirming it to be a member of the class I glutamine amidotransferase (GAT) family. Activity and substrate-binding assays confirm that SpuA exhibits a preference for γ-Glu-GABA as a substrate. Structures of an inactive H221N mutant were determined with bound glutamate thioester intermediate or glutamate product, thus delineating the active site and substrate-binding pocket and elucidating the catalytic mechanism. The crystal structure of another bacterial member of the class I GAT family from Mycolicibacterium smegmatis (MsGATase) in complex with glutamine was determined for comparison and reveals a binding site for glutamine. Activity assays confirm that MsGATase has activity for glutamine as a substrate but not for γ-Glu-GABA. The work reported here provides a starting point for further investigation of polyamine metabolism in P. aeruginosa.

Identification of FDA Approved Drugs Targeting COVID-19 Virus by Structure-Based Drug Repositioning (Version 2)

2020 ◽  
Author(s):  
Ayman Farag ◽  
Ping Wang ◽  
Mahmoud Ahmed ◽  
Hesham Sadek
Keyword(s):  
Drug Repositioning ◽  
Substrate Binding ◽  
Binding Pocket ◽  
Binding Energies ◽  
Binding Modes ◽  
Substrate Binding Pocket ◽  
Protease Enzyme ◽  
Starting Point ◽  
Approved Drugs ◽  
Fda Approved Drugs

The new strain of Coronaviruses (SARS-CoV-2), and the resulting Covid-19 disease has spread swiftly across the globe after its initial detection in late December 2019 in Wuhan, China, resulting in a pandemic status declaration by WHO within 3 months. Given the heavy toll of this pandemic, researchers are actively testing various strategies including new and repurposed drugs as well as vaccines. In the current brief report, we adopted a repositioning approach using insilico molecular modeling screening using FDA approved drugs with established safety profiles for potential inhibitory effects on Covid-19 virus. We started with structure based drug design by screening more than 2000 FDA approved drugs against Covid-19 virus main protease enzyme (Mpro) substrate-binding pocket focusing on two potential sites (central and terminal sites) to identify potential hits based on their binding energies, binding modes, interacting amino acids, and therapeutic indications. In addition, we elucidate preliminary pharmacophore features for candidates bound to Covid-19 virus Mpro substrate-binding pocket. The top hits bound to the central site of Mpro substrate-binding pocket include antiviral drugs such as Darunavir, Nelfinavir and Saquinavir, some of which are already being tested in Covid-19 patients. Interestingly, one of the most promising hits in our screen is the hypercholesterolemia drug Rosuvastatin. In addition, the top hits bound to the terminal site of Mpro substrate-binding pocket include the anti-asthma drug Montelukast and the anti-histaminic Fexofenadine among others. These results certainly do not confirm or indicate antiviral activity, but can rather be used as a starting point for further in vitro and in vivo testing, either individually or in combination.<br>

scholarly journals Carbapenemase NDM-1, Structural Analysis of the Catalytic Mechanism

2014 ◽  
Vol 70 (a1) ◽  
pp. C818-C818
Author(s):  
Youngchang Kim ◽  
Mark Cunningham ◽  
Christine Tesar ◽  
Robert Jedrzejczak ◽  
Joseph Mire ◽  
...  
Keyword(s):  
Catalytic Mechanism ◽  
Substrate Binding ◽  
Binding Pocket ◽  
New Delhi ◽  
Cadmium Ions ◽  
Ph Dependency ◽  
Its Gene ◽  
Different Strains ◽  
Global Threat ◽  
Energy Surfaces

The New Delhi Metallo β-lactamase (NDM-1), first identified in Klebsiella pneumoniae has been shown to hydrolyze nearly all clinical β-lactam antibiotics including carbapenems, considered "last resort" antibiotics. Its gene resides on mobile plasmids that move between different strains of bacteria posing a serious global threat to human health. There have also been reports of several variants, up to NDM-9, some with increased carbapenemase activity. As part of the NIGMS PSI:Biology effort, the Midwest Center for Structural Genomics (MCSG) together with the Structures of Mtb Proteins Conferring Susceptibility to Known Mtb Inhibitors partnership, made significant progress in investigating the enzyme atomic structure and catalytic mechanism. A large number of protein constructs as well as mutants were made and a number of high-resolution structures of NDM-1 (no Zn, one Zn, two Zn, two Mn or Cd, and complexed with antibiotics) and NDM-1 variants, NDM-2, NDM-3, NDM-4, NDM-5 and NDM-6 have been determined. We have determined the two structures of Michaelis complex: NDM-1 with two cadmium ions and a mixture of hydrolyzed and unhydrolyzed ampicillin (1.50 Å) and one with two cadmium ions and partly hydrolyzed faropenem (2.00 Å). The crystal structures revealed a ligand-binding pocket consisting of several flexible loops capable of accommodating many β-lactam substrates of different sizes and shapes. The structures with various metals suggest that the distance between the two metal atoms is closely correlated with substrate binding efficiency and hydrolysis and the pH-dependency of catalytic activity. For better understanding of catalytic mechanism of NDM-1, particularly the dynamics of substrate binding and the energy surfaces along the suggested reaction pathways, molecular dynamics calculations and hybrid classical/quantum (QM/MM) calculations were performed. This work was supported by NIH Grant GM094585 and by the U.S. DOE, OBER contract DE-AC02-06CH11357

scholarly journals The active site and substrate-binding mode of 1-aminocyclopropane-1-carboxylate oxidase determined by site-directed mutagenesis and comparative modelling studies

2004 ◽  
Vol 380 (2) ◽  
pp. 339-346 ◽  
Author(s):  
Young Sam SEO ◽  
Ahrim YOO ◽  
Jinwon JUNG ◽  
Soon-Kee SUNG ◽  
Dae Ryook YANG ◽  
...  
Keyword(s):  
Active Site ◽  
Catalytic Mechanism ◽  
Substrate Binding ◽  
Three Dimensional ◽  
Binding Pocket ◽  
Binding Mode ◽  
Site Directed Mutagenesis ◽  
Dimensional Structure ◽  
Directed Mutagenesis ◽  
Comparative Modelling

The active site and substrate-binding mode of MD-ACO1 (Malus domestica Borkh. 1-aminocyclopropane-1-carboxylate oxidase) have been determined using site-directed mutagenesis and comparative modelling methods. The MD-ACO1 protein folds into a compact jelly-roll motif comprised of eight α-helices, 12 β-strands and several long loops. The active site is well defined as a wide cleft near the C-terminus. The co-substrate ascorbate is located in cofactor Fe2+-binding pocket, the so-called ‘2-His-1-carboxylate facial triad’. In addition, our results reveal that Arg244 and Ser246 are involved in generating the reaction product during enzyme catalysis. The structure agrees well with the biochemical and site-directed mutagenesis results. The three-dimensional structure together with the steady-state kinetics of both the wild-type and mutant MD-ACO1 proteins reveal how the substrate specificity of MD-ACO1 is involved in the catalytic mechanism, providing insights into understanding the fruit ripening process at atomic resolution.

Identification of FDA Approved Drugs Targeting COVID-19 Virus by Structure-Based Drug Repositioning (Version 2)

2020 ◽  
Author(s):  
Ayman Farag ◽  
Ping Wang ◽  
Mahmoud Ahmed ◽  
Hesham Sadek
Keyword(s):  
Drug Repositioning ◽  
Substrate Binding ◽  
Binding Pocket ◽  
Binding Energies ◽  
Binding Modes ◽  
Substrate Binding Pocket ◽  
Protease Enzyme ◽  
Starting Point ◽  
Approved Drugs ◽  
Fda Approved Drugs

The new strain of Coronaviruses (SARS-CoV-2), and the resulting Covid-19 disease has spread swiftly across the globe after its initial detection in late December 2019 in Wuhan, China, resulting in a pandemic status declaration by WHO within 3 months. Given the heavy toll of this pandemic, researchers are actively testing various strategies including new and repurposed drugs as well as vaccines. In the current brief report, we adopted a repositioning approach using insilico molecular modeling screening using FDA approved drugs with established safety profiles for potential inhibitory effects on Covid-19 virus. We started with structure based drug design by screening more than 2000 FDA approved drugs against Covid-19 virus main protease enzyme (Mpro) substrate-binding pocket focusing on two potential sites (central and terminal sites) to identify potential hits based on their binding energies, binding modes, interacting amino acids, and therapeutic indications. In addition, we elucidate preliminary pharmacophore features for candidates bound to Covid-19 virus Mpro substrate-binding pocket. The top hits bound to the central site of Mpro substrate-binding pocket include antiviral drugs such as Darunavir, Nelfinavir and Saquinavir, some of which are already being tested in Covid-19 patients. Interestingly, one of the most promising hits in our screen is the hypercholesterolemia drug Rosuvastatin. In addition, the top hits bound to the terminal site of Mpro substrate-binding pocket include the anti-asthma drug Montelukast and the anti-histaminic Fexofenadine among others. These results certainly do not confirm or indicate antiviral activity, but can rather be used as a starting point for further in vitro and in vivo testing, either individually or in combination.<br>

scholarly journals Structure-Based Virtual Screening of Pseudomonas aeruginosa LpxA Inhibitors using Pharmacophore-Based Approach

Biomolecules ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 266
Author(s):  
Baki Vijaya Bhaskar ◽  
Tirumalasetty Muni Chandra Babu ◽  
Aluru Rammohan ◽  
Gui Yu Zheng ◽  
Grigory V. Zyryanov ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Virtual Screening ◽  
Lipid A ◽  
Catalytic Mechanism ◽  
Pharmacophore Model ◽  
Selective Inhibition ◽  
Binding Pocket ◽  
Uridine Diphosphate ◽  
Lead Compounds ◽  
Essential Enzyme

Multidrug resistance in Pseudomonas aeruginosa is a noticeable and ongoing major obstacle for inhibitor design. In P. aeruginosa, uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) acetyltransferase (PaLpxA) is an essential enzyme of lipid A biosynthesis and an attractive drug target. PaLpxA is a homotrimer, and the binding pocket for its substrate, UDP-GlcNAc, is positioned between the monomer A–monomer B interface. The uracil moiety binds at one monomer A, the GlcNAc moiety binds at another monomer B, and a diphosphate form bonds with both monomers. The catalytic residues are conserved and display a similar catalytic mechanism across orthologs, but some distinctions exist between pocket sizes, residue differences, substrate positioning and specificity. The analysis of diversified pockets, volumes, and ligand positions was determined between orthologues that could aid in selective inhibitor development. Thenceforth, a complex-based pharmacophore model was generated and subjected to virtual screening to identify compounds with similar pharmacophoric properties. Docking and general Born-volume integral (GBVI) studies demonstrated 10 best lead compounds with selective inhibition properties with essential residues in the pocket. For biological access, these scaffolds complied with the Lipinski rule, no toxicity and drug likeness properties, and were considered as lead compounds. Hence, these scaffolds could be helpful for the development of potential selective PaLpxA inhibitors.

scholarly journals Identification of FDA Approved Drugs Targeting COVID-19 Virus by Structure-Based Drug Repositioning

2020 ◽  
Author(s):  
Ayman Farag ◽  
Ping Wang ◽  
Mahmoud Ahmed ◽  
Hesham Sadek
Keyword(s):  
Drug Repositioning ◽  
Substrate Binding ◽  
Binding Pocket ◽  
Binding Energies ◽  
Binding Modes ◽  
Substrate Binding Pocket ◽  
Protease Enzyme ◽  
Starting Point ◽  
Approved Drugs ◽  
Fda Approved Drugs

<p>The new strain of Coronaviruses (SARS-CoV-2), and the resulting Covid-19 disease has spread swiftly across the globe after its initial detection in late December 2019 in Wuhan, China, resulting in a pandemic status declaration by WHO within 3 months. Given the heavy toll of this pandemic, researchers are actively testing various strategies including new and repurposed drugs as well as vaccines. In the current brief report, we adopted a repositioning approach using insilico molecular modeling screening using FDA approved drugs with established safety profiles for potential inhibitory effects on Covid-19 virus. We started with structure based drug design by screening more than 2000 FDA approved drugs against Covid-19 virus main protease enzyme (Mpro) substrate-binding pocket focusing on two potential sites (central and terminal sites) to identify potential hits based on their binding energies, binding modes, interacting amino acids, and therapeutic indications. In addition, we elucidate preliminary pharmacophore features for candidates bound to Covid-19 virus Mpro substrate-binding pocket. The top hits bound to the central site of Mpro substrate-binding pocket include antiviral drugs such as Darunavir, Nelfinavir and Saquinavir, some of which are already being tested in Covid-19 patients. Interestingly, one of the most promising hits in our screen is the hypercholesterolemia drug Rosuvastatin. In addition, the top hits bound to the terminal site of Mpro substrate-binding pocket include the anti-asthma drug Montelukast and the anti-histaminic Fexofenadine among others. These results certainly do not confirm or indicate antiviral activity, but can rather be used as a starting point for further in vitro and in vivo testing, either individually or in combination.</p>

scholarly journals Structural and catalytic characterization of Blastochloris viridis and Pseudomonas aeruginosa homospermidine synthases supports the essential role of cation–π interaction

2021 ◽  
Vol 77 (10) ◽  
Author(s):  
F. Helfrich ◽  
Axel J. Scheidig
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Crystal Structures ◽  
Active Site ◽  
Structural Similarity ◽  
Opportunistic Pathogen ◽  
Binding Pocket ◽  
Polyamine Metabolism ◽  
Tryptophan Residue ◽  
Salt Bridges ◽  
Blastochloris Viridis

Polyamines influence medically relevant processes in the opportunistic pathogen Pseudomonas aeruginosa, including virulence, biofilm formation and susceptibility to antibiotics. Although homospermidine synthase (HSS) is part of the polyamine metabolism in various strains of P. aeruginosa, neither its role nor its structure has been examined so far. The reaction mechanism of the nicotinamide adenine dinucleotide (NAD+)-dependent bacterial HSS has previously been characterized based on crystal structures of Blastochloris viridis HSS (BvHSS). This study presents the crystal structure of P. aeruginosa HSS (PaHSS) in complex with its substrate putrescine. A high structural similarity between PaHSS and BvHSS with conservation of the catalytically relevant residues is demonstrated, qualifying BvHSS as a model for mechanistic studies of PaHSS. Following this strategy, crystal structures of single-residue variants of BvHSS are presented together with activity assays of PaHSS, BvHSS and BvHSS variants. For efficient homospermidine production, acidic residues are required at the entrance to the binding pocket (`ionic slide') and near the active site (`inner amino site') to attract and bind the substrate putrescine via salt bridges. The tryptophan residue at the active site stabilizes cationic reaction components by cation–π interaction, as inferred from the interaction geometry between putrescine and the indole ring plane. Exchange of this tryptophan for other amino acids suggests a distinct catalytic requirement for an aromatic interaction partner with a highly negative electrostatic potential. These findings substantiate the structural and mechanistic knowledge on bacterial HSS, a potential target for antibiotic design.

scholarly journals Identification of FDA Approved Drugs Targeting COVID-19 Virus by Structure-Based Drug Repositioning

2020 ◽  
Author(s):  
Ayman Farag ◽  
Ping Wang ◽  
Mahmoud Ahmed ◽  
Hesham Sadek
Keyword(s):  
Drug Repositioning ◽  
Substrate Binding ◽  
Binding Pocket ◽  
Binding Energies ◽  
Binding Modes ◽  
Substrate Binding Pocket ◽  
Protease Enzyme ◽  
Starting Point ◽  
Approved Drugs ◽  
Fda Approved Drugs

<p>The new strain of Coronaviruses (SARS-CoV-2), and the resulting Covid-19 disease has spread swiftly across the globe after its initial detection in late December 2019 in Wuhan, China, resulting in a pandemic status declaration by WHO within 3 months. Given the heavy toll of this pandemic, researchers are actively testing various strategies including new and repurposed drugs as well as vaccines. In the current brief report, we adopted a repositioning approach using insilico molecular modeling screening using FDA approved drugs with established safety profiles for potential inhibitory effects on Covid-19 virus. We started with structure based drug design by screening more than 2000 FDA approved drugs against Covid-19 virus main protease enzyme (Mpro) substrate-binding pocket focusing on two potential sites (central and terminal sites) to identify potential hits based on their binding energies, binding modes, interacting amino acids, and therapeutic indications. In addition, we elucidate preliminary pharmacophore features for candidates bound to Covid-19 virus Mpro substrate-binding pocket. The top hits bound to the central site of Mpro substrate-binding pocket include antiviral drugs such as Darunavir, Nelfinavir and Saquinavir, some of which are already being tested in Covid-19 patients. Interestingly, one of the most promising hits in our screen is the hypercholesterolemia drug Rosuvastatin. In addition, the top hits bound to the terminal site of Mpro substrate-binding pocket include the anti-asthma drug Montelukast and the anti-histaminic Fexofenadine among others. These results certainly do not confirm or indicate antiviral activity, but can rather be used as a starting point for further in vitro and in vivo testing, either individually or in combination.</p>

Copper–oxygen Dynamics in Tyrosinase

2019 ◽  
Author(s):  
Nobutaka Fujieda ◽  
Sachiko Yanagisawa ◽  
Minoru Kubo ◽  
Genji Kurisu ◽  
Shinobu Itoh
Keyword(s):  
Catalytic Mechanism ◽  
Substrate Binding ◽  
Active Form ◽  
Copper Ion ◽  
Atomic Resolution ◽  
Oxygen Species ◽  
X Ray ◽  
Oxygen Dynamics ◽  
Insight Into ◽  
Copper Centre

To unveil the activation of dioxygen on the copper centre (Cu<sub>2</sub>O<sub>2</sub>core) of tyrosinase, we performed X-ray crystallograpy with active-form tyrosinase at near atomic resolution. This study provided a novel insight into the catalytic mechanism of the tyrosinase, including the rearrangement of copper-oxygen species as well as the intramolecular migration of copper ion induced by substrate-binding.<br>

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