scholarly journals Unique Pharmacological Properties of α-Conotoxin OmIA at α7 nAChRs

2021 ◽  
Vol 12 ◽  
Author(s):  
Thao N.T. Ho ◽  
Nikita Abraham ◽  
Richard J. Lewis
Keyword(s):  
Crystal Structure ◽  
Prolonged Exposure ◽  
Tight Binding ◽  
Binding Mode ◽  
Pharmacological Properties ◽  
Acetylcholine Binding Protein ◽  
Step Model ◽  
High Affinity Binding Site ◽  
Potent Antagonist ◽  
Α7 Nachrs

OmIA, isolated from Conus omaria venom, is a potent antagonist at α7 nAChRs. We determined the co-crystal structure of OmIA with Lymnae stagnalis acetylcholine binding protein (Ls-AChBP) that identified His5, Val10 and Asn11 as key determinants for the high potency of OmIA at α7 nAChRs. Remarkably, despite a competitive binding mode observed in the co-crystal structure, OmIA and analogues displayed functional insurmountable antagonism at α7 and α3β4 nAChRs, except OmIA analogues having long side chain at position 10 ([V10Q]OmIA and [V10L]OmIA), which were partial insurmountable antagonist at α7 nAChRs in the presence of type II positive allosteric modulators (PAMs). A “two-state, two-step” model was used to explain these observations, with [V10Q]OmIA and [V10L]OmIA co-existing in a fast reversible/surmountable as well as a tight binding/insurmountable state. OmIA and analogues also showed biphasic-inhibition at α7 nAChRs in the presence of PNU120596, with a preference for the high-affinity binding site following prolonged exposure. The molecular basis of binding and complex pharmacological profile of OmIA at α7 nAChRs presented in here expands on the potential of α-conotoxins to probe the pharmacological properties of nAChRs and may help guide the development novel α7 modulators.

scholarly journals Slow-onset inhibition of fumarylacetoacetate hydrolase by phosphinate mimics of the tetrahedral intermediate: kinetics, crystal structure and pharmacokinetics

2007 ◽  
Vol 402 (2) ◽  
pp. 251-260 ◽  
Author(s):  
Raynard L. Bateman ◽  
Justin Ashworth ◽  
John F. Witte ◽  
L.-J. Baker ◽  
Pullooru Bhanumoorthy ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Tight Binding ◽  
Binding Mode ◽  
Mouse Serum ◽  
Liver Protein ◽  
Tyrosinaemia Type ◽  
Tetrahedral Intermediate ◽  
Fumarylacetoacetate Hydrolase ◽  
Slow Onset

FAH (fumarylacetoacetate hydrolase) catalyses the final step of tyrosine catabolism to produce fumarate and acetoacetate. HT1 (hereditary tyrosinaemia type 1) results from deficiency of this enzyme. Previously, we prepared a partial mimic of the putative tetrahedral intermediate in the reaction catalysed by FAH co-crystallized with the enzyme to reveal details of the mechanism [Bateman, Bhanumoorthy, Witte, McClard, Grompe and Timm (2001) J. Biol. Chem. 276, 15284–15291]. We have now successfully synthesized complete mimics CEHPOBA {4-[(2-carboxyethyl)-hydroxyphosphinyl]-3-oxobutyrate} and COPHPAA {3-[(3-carboxy-2-oxopropyl)hydroxyphosphinyl]acrylate}, which inhibit FAH in slow-onset tight-binding mode with Ki values of 41 and 12 nM respectively. A high-resolution (1.35 Å; 1 Å=0.1 nm) crystal structure of the FAH·CEHPOBA complex was solved to reveal the affinity determinants for these compounds and to provide further insight into the mechanism of FAH catalysis. These compounds are active in vivo, and CEHPOBA demonstrated a notable dose-dependent increase in SA (succinylacetone; a metabolite seen in patients with HT1) in mouse serum after repeated injections, and, following a single injection (1 μmol/g; intraperitoneal), only a modest regain of FAH enzyme activity was detected in liver protein isolates after 24 h. These potent inhibitors provide a means to chemically phenocopy the metabolic defects of either HT1 or FAH knockout mice and promise future pharmacological utility for hepatocyte transplantation.

Ruthenium(II) Complexes Bearing Thioether-Appended α- Iminopyridine Ligands: Arene Precursors Permit Access to K2-N,N and K3-N,N,S Complexes

2019 ◽  
Author(s):  
Victoria A. Ternes ◽  
Hannah A. Morgan ◽  
Austin P. Lanquist ◽  
Michael P. Murray ◽  
Bradley Wile
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Strong Field ◽  
Active Role ◽  
Binding Mode ◽  
Phenethyl Alcohol ◽  
Ru Complexes

Herein we report the preparation of a series of Ru(II) complexes featuring alpha-iminopyridine ligands bearing thioether functionality (NNS<sup>R</sup>, where R = Me, CH<sub>2</sub>Ph, Ph). Metallation using (<i>p</i> cymene)RuCl dimer permits access to (k<sup>2</sup>-N,N)Ru complexes in which the thioether moiety remains uncoordinated. In the presence of a strong field ligand such as acetonitrile or triphenylphosphine, the p-cymene moiety is displaced, and the ligand adopts a k<sup>3</sup>-N,N,S binding mode. These complexes are characterized using a combination of solution and solid state methods, including the crystal structure of [(NNS<sup>Me</sup>)Ru(NCMe)<sub>2</sub>Cl]Cl. The k<sup>2</sup>-N,N Ru(II) complexes are shown to serve as efficient precatalysts for the oxidation of sec-phenethyl alcohol at 5 mol% loadings, using a variety of external oxidants and solvents. The complex bearing an S-Ph donor was found to be the most active of those surveyed, suggesting that the thioether donor plays an active role in catalyst speciation for this transformation.

scholarly journals Crystal structures of Ca2+–calmodulin bound to NaV C-terminal regions suggest role for EF-hand domain in binding and inactivation

2019 ◽  
Vol 116 (22) ◽  
pp. 10763-10772 ◽  
Author(s):  
Bernd R. Gardill ◽  
Ricardo E. Rivera-Acevedo ◽  
Ching-Chieh Tung ◽  
Filip Van Petegem
Keyword(s):  
Crystal Structure ◽  
Binding Sites ◽  
Binding Mode ◽  
Conformational Switch ◽  
Channel Inactivation ◽  
Dependent Inactivation ◽  
Ef Hand ◽  
Inherited Arrhythmia ◽  
A Site

Voltage-gated sodium (NaV) and calcium channels (CaV) form targets for calmodulin (CaM), which affects channel inactivation properties. A major interaction site for CaM resides in the C-terminal (CT) region, consisting of an IQ domain downstream of an EF-hand domain. We present a crystal structure of fully Ca2+-occupied CaM, bound to the CT of NaV1.5. The structure shows that the C-terminal lobe binds to a site ∼90° rotated relative to a previous site reported for an apoCaM complex with the NaV1.5 CT and for ternary complexes containing fibroblast growth factor homologous factors (FHF). We show that the binding of FHFs forces the EF-hand domain in a conformation that does not allow binding of the Ca2+-occupied C-lobe of CaM. These observations highlight the central role of the EF-hand domain in modulating the binding mode of CaM. The binding sites for Ca2+-free and Ca2+-occupied CaM contain targets for mutations linked to long-QT syndrome, a type of inherited arrhythmia. The related NaV1.4 channel has been shown to undergo Ca2+-dependent inactivation (CDI) akin to CaVs. We present a crystal structure of Ca2+/CaM bound to the NaV1.4 IQ domain, which shows a binding mode that would clash with the EF-hand domain. We postulate the relative reorientation of the EF-hand domain and the IQ domain as a possible conformational switch that underlies CDI.

scholarly journals Crystal Structure of the Streptomyces coelicolor Sortase E1 Transpeptidase Provides Insight into the Binding Mode of the Novel Class E Sorting Signal

PLoS ONE ◽  
2016 ◽  
Vol 11 (12) ◽  
pp. e0167763 ◽  
Author(s):  
Michele D. Kattke ◽  
Albert H. Chan ◽  
Andrew Duong ◽  
Danielle L. Sexton ◽  
Michael R. Sawaya ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Streptomyces Coelicolor ◽  
Binding Mode ◽  
The Novel ◽  
Sorting Signal ◽  
Insight Into ◽  
Class E

scholarly journals Mechanism of action and NAD+-binding mode revealed by the crystal structure of L-histidinol dehydrogenase

2002 ◽  
Vol 99 (4) ◽  
pp. 1859-1864 ◽  
Author(s):  
J. A. R. G. Barbosa ◽  
J. Sivaraman ◽  
Y. Li ◽  
R. Larocque ◽  
A. Matte ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Mechanism Of Action ◽  
Binding Mode ◽  
Histidinol Dehydrogenase

scholarly journals Cyclic Boronates Inhibit All Classes of β-Lactamases

2017 ◽  
Vol 61 (4) ◽  
Author(s):  
Samuel T. Cahill ◽  
Ricky Cain ◽  
David Y. Wang ◽  
Christopher T. Lohans ◽  
David W. Wareham ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Bacterial Infections ◽  
Binding Mode ◽  
Gram Negative ◽  
Content Type ◽  
Class A ◽  
Class D ◽  
Dual Action ◽  
The Common ◽  
Continued Use

ABSTRACT β-Lactamase-mediated resistance is a growing threat to the continued use of β-lactam antibiotics. The use of the β-lactam-based serine-β-lactamase (SBL) inhibitors clavulanic acid, sulbactam, and tazobactam and, more recently, the non-β-lactam inhibitor avibactam has extended the utility of β-lactams against bacterial infections demonstrating resistance via these enzymes. These molecules are, however, ineffective against the metallo-β-lactamases (MBLs), which catalyze their hydrolysis. To date, there are no clinically available metallo-β-lactamase inhibitors. Coproduction of MBLs and SBLs in resistant infections is thus of major clinical concern. The development of “dual-action” inhibitors, targeting both SBLs and MBLs, is of interest, but this is considered difficult to achieve due to the structural and mechanistic differences between the two enzyme classes. We recently reported evidence that cyclic boronates can inhibit both serine- and metallo-β-lactamases. Here we report that cyclic boronates are able to inhibit all four classes of β-lactamase, including the class A extended spectrum β-lactamase CTX-M-15, the class C enzyme AmpC from Pseudomonas aeruginosa, and class D OXA enzymes with carbapenem-hydrolyzing capabilities. We demonstrate that cyclic boronates can potentiate the use of β-lactams against Gram-negative clinical isolates expressing a variety of β-lactamases. Comparison of a crystal structure of a CTX-M-15:cyclic boronate complex with structures of cyclic boronates complexed with other β-lactamases reveals remarkable conservation of the small-molecule binding mode, supporting our proposal that these molecules work by mimicking the common tetrahedral anionic intermediate present in both serine- and metallo-β-lactamase catalysis.

scholarly journals Crystal structure reveals a unique ABIN-Ubs binding mode

2019 ◽  
Vol 75 (a1) ◽  
pp. a22-a22
Author(s):  
Jhen-Yi Hong ◽  
Su-Chang Lin ◽  
Yu-Chih Lo
Keyword(s):  
Crystal Structure ◽  
Binding Mode

scholarly journals Co-crystal structure of Protein kinase C-iota with inhibitor reveals a unique binding mode

2019 ◽  
Vol 75 (a1) ◽  
pp. a52-a52
Author(s):  
Nithya Baburajendran ◽  
Jacek Kwiatkowski ◽  
Boping Liu ◽  
Doris Hui Ying Tee ◽  
Thomas H. Keller ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Binding Mode ◽  
Kinase C ◽  
Protein Kinase C Iota

scholarly journals Crystal Structure of Calmodulin Binding Domain of Orai1 in Complex with Ca2+•Calmodulin Displays a Unique Binding Mode

2012 ◽  
Vol 287 (51) ◽  
pp. 43030-43041 ◽  
Author(s):  
Yanshun Liu ◽  
Xunhai Zheng ◽  
Geoffrey A. Mueller ◽  
Mack Sobhany ◽  
Eugene F. DeRose ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Binding Mode ◽  
Binding Domain ◽  
Calmodulin Binding
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