Cristalización de proteínas en el diseño de fármacos en los últimos 50 años

We live in an era where we expect to be able to visit our doctor and obtain a pill to cure any ailment from which we suffer. Yet, this is still not the case. Many of the current cures are still derived from natural sources although new drugs are increasingly the result of intelligent design. In this process, X-ray protein crystallography now plays a major and effective role in the discovery of new treatments. The developments that have made this possible have evolved during the past fifty years. The methods for crystallizing macromolecules and determining their structures by X-ray crystallography have been automated and the speed for X-ray data acquisition is several orders of magnitude faster. Fifty years ago it took several years to solve a single structure. Now, several protein–ligand complexes can be determined in single day. High-throughput crystallography is considered to be a great asset to the drug discovery process, providing a fast way to tailor drug candidates to their targets by analysing their binding mode in detail. Crystallization remains the main challenge.Vivimos en una época en la que esperamos ir al médico y obtener una pastilla para curar cualquier dolencia que padezcamos; por desgracia, esta expectativa no es real. Aunque muchos de los remedios en uso provienen de fuentes naturales, la mayoría de los nuevos medicamentos son el resultado de la investigación científica. En el proceso de diseño y descubrimiento de fármacos, la cristalografía de proteínas juega un papel central. Los conocimientos que han hecho esto posible han venido evolucionando desde hace cincuenta años aproximadamente. Los métodos de cristalización de macromoléculas y la determinación de sus estructuras a través de la cristalografía de rayos X han sido automatizados y miniaturizados y la velocidad de la adquisición de datos de difracción ha aumentado en varios órdenes de magnitud. Si hace cincuenta años la resolución de una sola estructura podría llevar varios años, actualmente se pueden determinar las estructuras de varios complejos proteína-ligando en un solo día. La cristalografía de alto rendimiento hoy día es un gran recurso en el proceso del descubrimiento de fármacos pues proporciona una manera rápida y precisa de adaptar los fármacos candidatos a las dianas mediante el análisis de su modo de unión. La cristalización sigue siendo el principal desafío

Transthyretin complexes with curcumin and bromo-estradiol: Evaluation of solubilizing multicomponent mixtures

Crystallographic structure determination of protein–ligand complexes of transthyretin (TTR) has been hindered by the low affinity of many compounds that bind to the central cavity of the tetramer. Because crystallization trials are carried out at protein and ligand concentration that approach the millimolar range, low affinity is less of a problem than the poor solubility of many compounds that have been shown to inhibit amyloid fibril formation. To achieve complete occupancy in co-crystallization experiments, the minimal requirement is one ligand for each of the two sites within the TTR tetramer. Here we present a new strategy for the co-crystallization of TTR using high molecular weight polyethylene glycol instead of high ionic strength precipitants, with ligands solubilized in multicomponent mixtures of compounds. This strategy is applied to the crystallization of TTR complexes with curcumin and 16a-bromo-estradiol. Here we report the crystal structures with these compounds and with the ferulic acid that results from curcumin degradation

Halogen Bonding Controls Selectivity of FRET Substrate Probes for MMP-9

SummaryMatrix metalloproteinases (MMPs) are a large family of zinc-dependent endoproteases that catalyze cleavage of extracellular matrix and nonmatrix proteins. MMPs play a role in tissue remodeling, and their uncontrolled activity is associated with number of diseases, including tumor metastasis. Thus, there is a need to develop methods to monitor MMP activity, and number of probes has been previously described. The key problem many probes encounter is the issue of selectivity, since 23 human MMPs, despite playing different physiological roles, have structurally similar active sites. Here, we introduce the halogen bonding concept into the probe design and show that the probe containing iodine exhibits an unprecedented selectivity for MMP-9. We provide structure-based explanation for the selectivity, confirming that it is due to formation of the halogen bond that supports catalysis, and we highlight the value of exploring halogen bonding in the context of selective probe design

Discovery of a new selective inhibitor of A Disintegrin And Metalloprotease 10 (ADAM-10) able to reduce the shedding of NKG2D ligands in Hodgkin's lymphoma cell models

Hodgkin's lymphoma (HL) is the most common malignant lymphoma in young adults in the western world. This disease is characterized by an overexpression of ADAM-10 with increased release of NKG2D ligands, involved in an impaired immune response against tumor cells. We designed and synthesized two new ADAM-10 selective inhibitors, 2 and 3 based on previously published ADAM-17 selective inhibitor 1. The most promising compound was the thiazolidine derivative 3, with nanomolar activity for ADAM-10, high selectivity over ADAM-17 and MMPs and good efficacy in reducing the shedding of NKG2D ligands (MIC-B and ULBP3) in three different HL cell lines at non-toxic doses. Molecular modeling studies were used to drive the design and X-ray crystallography studies were carried out to explain the selectivity of 3 for ADAM-10 over MMPs

Copper mediated amyloid-β binding to Transthyretin

Transthyretin (TTR), a homotetrameric protein that transports thyroxine and retinol both in plasma and in cerebrospinal (CSF) fluid provides a natural protective response against Alzheimer’s disease (AD), modulates amyloid-β (Aβ) deposition by direct interaction and co-localizes with Aβ in plaques. TTR levels are lower in the CSF of AD patients. Zn2+, Mn2+and Fe2+transform TTR into a protease able to cleave Aβ. To explain these activities, monomer dissociation or conformational changes have been suggested. Here, we report that when TTR crystals are exposed to copper or iron salts, the tetramer undergoes a significant conformational change that alters the dimer-dimer interface and rearranges residues implicated in TTR’s ability to neutralize Aβ. We also describe the conformational changes in TTR upon the binding of the various metal ions. Furthermore, using bio-layer interferometry (BLI) with immobilized Aβ(1–28), we observe the binding of TTR only in the presence of copper. Such Cu2+-dependent binding suggests a recognition mechanism whereby Cu2+modulates both the TTR conformation, induces a complementary Aβ structure and may participate in the interaction. Cu2+-soaked TTR crystals show a conformation different from that induced by Fe2+, and intriguingly, TTR crystals grown in presence of Aβ(1–28) show different positions for the copper sites from those grown its absence

Engineering of Three-Finger Fold Toxins Creates Ligands with Original Pharmacological Profiles for Muscarinic and Adrenergic Receptors

Protein engineering approaches are often a combination of rational design and directed evolution using display technologies. Here, we test “loop grafting,” a rational design method, on three-finger fold proteins. These small reticulated proteins have exceptional affinity and specificity for their diverse molecular targets, display protease-resistance, and are highly stable and poorly immunogenic. The wealth of structural knowledge makes them good candidates for protein engineering of new functionality. Our goal is to enhance the efficacy of these mini-proteins by modifying their pharmacological properties in order to extend their use in imaging, diagnostics and therapeutic applications. Using the interaction of three-finger fold toxins with muscarinic and adrenergic receptors as a model, chimeric toxins have been engineered by substituting loops on toxin MT7 by those from toxin MT1. The pharmacological impact of these grafts was examined using binding experiments on muscarinic receptors M1 and M4 and on the α1A-adrenoceptor. Some of the designed chimeric proteins have impressive gain of function on certain receptor subtypes achieving an original selectivity profile with high affinity for muscarinic receptor M1 and α1A-adrenoceptor. Structure-function analysis supported by crystallographic data for MT1 and two chimeras permits a molecular based interpretation of these gains and details the merits of this protein engineering technique. The results obtained shed light on how loop permutation can be used to design new three-finger proteins with original pharmacological profiles

Protein crystallization for drug design in the last 50 years

We live in an era where we expect to be able to visit our doctor and obtain a pill to cure any ailment from which we suffer. Yet, this is still not the case. Many of the current cures are still derived from natural sources although new drugs are increasingly the result of intelligent design. In this process, X-ray protein crystallography now plays a major and effective role in the discovery of new treatments. The developments that have made this possible have evolved during the past fifty years. The methods for crystallizing macromolecules and determining their structures by X-ray crystallography have been automated and the speed for X-ray data acquisition is several orders of magnitude faster. Fifty years ago it took several years to solve a single structure. Now, several protein–ligand complexes can be determined in single day. High-throughput crystallography is considered to be a great asset to the drug discovery process, providing a fast way to tailor drug candidates to their targets by analysing their binding mode in detail. Crystallization remains the main challenge.<br><br>Vivimos en una época en la que esperamos ir al médico y obtener una pastilla para curar cualquier dolencia que padezcamos; por desgracia, esta expectativa no es real. Aunque muchos de los remedios en uso provienen de fuentes naturales, la mayoría de los nuevos medicamentos son el resultado de la investigación científica. En el proceso de diseño y descubrimiento de fármacos, la cristalografía de proteínas juega un papel central. Los conocimientos que han hecho esto posible han venido evolucionando desde hace cincuenta años aproximadamente. Los métodos de cristalización de macromoléculas y la determinación de sus estructuras a través de la cristalografía de rayos X han sido automatizados y miniaturizados y la velocidad de la adquisición de datos de difracción ha aumentado en varios órdenes de magnitud. Si hace cincuenta años la resolución de una sola estructura podría llevar varios años, actualmente se pueden determinar las estructuras de varios complejos proteína-ligando en un solo día. La cristalografía de alto rendimiento hoy día es un gran recurso en el proceso del descubrimiento de fármacos pues proporciona una manera rápida y precisa de adaptar los fármacos candidatos a las dianas mediante el análisis de su modo de unión. La cristalización sigue siendo el principal desafío

Human TTR Conformation Altered by Rhenium Tris-Carbonyl Derivatives

International audienceTransthyretin (TTR) is a 54\,kDa homotetrameric serum protein that transports thyroxine (T4) and retinol. TTR is potentially amyloidogenic due to homotetramer dissociation into monomeric intermediates that self-assemble as amyloid deposits and insoluble fibrils. Most crystallographic structures, including those of amyloidogenic variants show the same tetramer without major variations in the monomer-monomer interface nor in the volume of the interdimeric cavity. Soaking TTR crystals in a solution containing rhenium tris-carbonyl derivatives yields a TTR conformer never observed before. Only one of the two monomers of the crystallographic dimer is significantly altered, and the inner part of the T4 binding cavity is expanded at one end and shrunk at the other. The result redefines the mechanism of allosteric communication between the two sites, suggesting that negative cooperativity is a function of dimer asymmetry, which can be induced through internal or external binding. An aspect that remains unexplained is why the conformational changes are ubiquitous throughout the crystal although the heavy metal content of the derivatized crystals is relatively low. The conformational changes observed, which include Leu82, may represent a form of TTR better at scavenging β-Amyloid. At a resolution of 1.69Å, with excellent refinement statistics and well defined electron density for all parts of the structure, it is possible to envisage answering important questions that range from protein cooperative behavior to heavy atom induced protein conformational modifications that can result in crystallographic non-isomorphism