Functional Implications of Second-Shell Basic Residues for dUTPase DR2231 Enzymatic Specificity

Nucleotide-processing enzymes are key players in biological processes. They often operate through high substrate specificity for catalysis. How such specificity is achieved is unclear. Here, we dea..

Computational investigations of polymerase enzymes: Structure, function, inhibition, and biotechnology

AbstractDNA and RNA polymerases (Pols) are central to life, health, and biotechnology because they allow the flow of genetic information in biological systems. Importantly, Pol function and (de)regulation are linked to human diseases, notably cancer (DNA Pols) and viral infections (RNA Pols) such as COVID‐19. In addition, Pols are used in various applications such as synthesis of artificial genetic polymers and DNA amplification in molecular biology, medicine, and forensic analysis. Because of all of this, the field of Pols is an intense research area, in which computational studies contribute to elucidating experimentally inaccessible atomistic details of Pol function. In detail, Pols catalyze the replication, transcription, and repair of nucleic acids through the addition, via a nucleotidyl transfer reaction, of a nucleotide to the 3′‐end of the growing nucleic acid strand. Here, we analyze how computational methods, including force‐field‐based molecular dynamics, quantum mechanics/molecular mechanics, and free energy simulations, have advanced our understanding of Pols. We examine the complex interaction of chemical and physical events during Pol catalysis, like metal‐aided enzymatic reactions for nucleotide addition and large conformational rearrangements for substrate selection and binding. We also discuss the role of computational approaches in understanding the origin of Pol fidelity—the ability of Pols to incorporate the correct nucleotide that forms a Watson–Crick base pair with the base of the template nucleic acid strand. Finally, we explore how computations can accelerate the discovery of Pol‐targeting drugs and engineering of artificial Pols for synthetic and biotechnological applications.This article is categorized under: Structure and Mechanism > Reaction Mechanisms and Catalysis Structure and Mechanism > Computational Biochemistry and Biophysics Software > Molecular Modelin

Modeling Kinetics and Thermodynamics of Guest Encapsulation into the [ML] 12- Supramolecular Organometallic Cage

Altres ajuts: Acord transformatiu CRUE-CSICThe encapsulation of molecular guests into supramolecular hosts is a complex molecular recognition process in which the guest displaces the solvent from the host cavity, while the host deforms to let the guest in. An atomistic description of the association would provide valuable insights on the physicochemical properties that guide it. This understanding may be used to design novel host assemblies with improved properties (i.e., affinities) toward a given class of guests. Molecular simulations may be conveniently used to model the association processes. It is thus of interest to establish efficient protocols to trace the encapsulation process and to predict the associated magnitudes Δ G and Δ G ⧧. Here, we report the calculation of the Gibbs energy barrier and Gibbs binding energy by means of explicit solvent molecular simulations for the [GaL] 12- metallocage encapsulating a series of cationic molecules. The Δ G ⧧ for encapsulation was estimated by means of umbrella sampling simulations. The steps involved were identified, including ion-pair formation and naphthalene rotation (from L ligands of the metallocage) during the guest's entrance. The Δ G values were computed using the attach-pull-release method. The results reveal the sensitivity of the estimates on the force field parameters, in particular on atomic charges, showing that higher accuracy is obtained when charges are derived from implicit solvent quantum chemical calculations. Correlation analysis identified some indicators for the binding affinity trends. All computed magnitudes are in very good agreement with experimental observations. This work provides, on one side, a benchmarked way to computationally model a highly charged metallocage encapsulation process. This includes a nonstandard parameterization and charge derivation procedure. On the other hand, it gives specific mechanistic information on the binding processes of [GaL] 12- at the molecular level where key motions are depicted. Taken together, the study provides an interesting option for the future design of metal-organic cages

A Tetraferrocenyl-Resorcinarene Cavitand as a Redox-Switchable Host of Ammonium Salts

Tetraannulation of a resorcinarene-octaamino cavitand with ferrocenecarboxaldehyde allows the preparation of a tetrabenzimidazole-resorcinarene cavitand with four ferrocenyl moieties directly linked to the C2 atom of the imidazole units. Oxidation of the four ferrocenyl moieties produces important structural modifications of the molecule, as indicated by DFT calculations performed for the neutral and tetraoxidized forms of the cavitand. By means of 1H NMR spectroscopic analysis, the encapsulating properties of the new tetraferrocenyl-resorcinarene cavitand toward a series of ammonium salts were evaluated, and a clear cutoff point in binding affinity with respect to size was observed. Cyclic voltammetric studies allowed us to estimate the relative association constants for the neutral and oxidized forms of the cavitand, thus indicating that the guest was bound to the neutral (reduced) state of the cavitand and was released from the oxidized form. These redox-addressable conformational and binding properties of the resorcinarene-tetraferrocenyl cavitand constitute all the necessary features of a redox-switchable molecular gripper. By means of mass-spectrometric analysis, we could unambiguously confirm the molar stoichiometry of the host–guest complex (1:1) and assess the strong guest encapsulation, as indicated by triggering the covalent coupling between host and guest in the gas phase.MEC of Spain (CTQ2011-24055/BQU and CTQ2014-54071-P) and the Universitat Jaume I (P11B2014-02

A Self-Activated Mechanism for Nucleic Acid Polymerization Catalyzed by DNA/RNA Polymerases

The enzymatic polymerization of DNA and RNA is the basis for genetic inheritance for all living organisms. It is catalyzed by the DNA/RNA polymerase (Pol) superfamily. Here, bioinformatics analysis reveals that the incoming nucleotide substrate always forms an H-bond between its 3′-OH and β-phosphate moieties upon formation of the Michaelis complex. This previously unrecognized H-bond implies a novel self-activated mechanism (SAM), which synergistically connects the in situ nucleophile formation with subsequent nucleotide addition and, importantly, nucleic acid translocation. Thus, SAM allows an elegant and efficient closed-loop sequence of chemical and physical steps for Pol catalysis. This is markedly different from previous mechanistic hypotheses. Our proposed mechanism is corroborated via ab initio QM/MM simulations on a specific Pol, the human DNA polymerase-η, an enzyme involved in repairing damaged DNA. The structural conservation of DNA and RNA Pols supports the possible extension of SAM to Pol enzymes from the three domains of life

A Self-Activated Mechanism for Nucleic Acid Polymerization Catalyzed by DNA/RNA Polymerases

The enzymatic polymerization of DNA and RNA is the basis for genetic inheritance for all living organisms. It is catalyzed by the DNA/RNA polymerase (Pol) superfamily. Here, bioinformatics analysis reveals that the incoming nucleotide substrate always forms an H-bond between its 3′-OH and β-phosphate moieties upon formation of the Michaelis complex. This previously unrecognized H-bond implies a novel self-activated mechanism (SAM), which synergistically connects the in situ nucleophile formation with subsequent nucleotide addition and, importantly, nucleic acid translocation. Thus, SAM allows an elegant and efficient closed-loop sequence of chemical and physical steps for Pol catalysis. This is markedly different from previous mechanistic hypotheses. Our proposed mechanism is corroborated via ab initio QM/MM simulations on a specific Pol, the human DNA polymerase-η, an enzyme involved in repairing damaged DNA. The structural conservation of DNA and RNA Pols supports the possible extension of SAM to Pol enzymes from the three domains of life

Design of an enantioselective artificial metallo-hydratase enzyme containing an unnatural metal-binding amino acid

The design of artificial metalloenzymes is a challenging, yet ultimately highly rewarding objective because of the potential for accessing new-to-nature reactions. One of the main challenges is identifying catalytically active substrate-metal cofactor-host geometries. The advent of expanded genetic code methods for the in vivo incorporation of non-canonical metal-binding amino acids into proteins allow to address an important aspect of this challenge: the creation of a stable, well-defined metal-binding site. Here, we report a designed artificial metallohydratase, based on the transcriptional repressor lactococcal multidrug resistance regulator (LmrR), in which the non-canonical amino acid (2,2'-bipyridin-5yl) alanine is used to bind the catalytic Cu(II) ion. Starting from a set of empirical pre-conditions, a combination of cluster model calculations (QM), protein-ligand docking and molecular dynamics simulations was used to propose metallohydratase variants, that were experimentally verified. The agreement observed between the computationally predicted and experimentally observed catalysis results demonstrates the power of the artificial metalloenzyme design approach presented here