Spy vs. spy: selecting the best reporter for 19F NMR competition experiments.
Ontology highlight
ABSTRACT:
SUBMITTER: de Castro GV
PROVIDER: S-EPMC6369734 | biostudies-literature | 2019 Jan
REPOSITORIES: biostudies-literature
Publications
Spy vs. spy: selecting the best reporter for <sup>19</sup>F NMR competition experiments.
de Castro Guilherme Vieira GV Ciulli Alessio A
Chemical communications (Cambridge, England) 20190101 10
Systematic characterization of a series of fluorinated VHL ligands, varying binding affinity and position of the trifluoromethyl group, qualifies a spy molecule for competitive 19F NMR screening and reveals guiding principles to develop highly sensitive assays with low material consumption. ...[more]
Similar Datasets
Project description:Riboflavin synthase catalyzes the transformation of 6,7-dimethyl-8-ribityllumazine into riboflavin in the last step of the riboflavin biosynthetic pathway. Gram-negative bacteria and certain yeasts are unable to incorporate riboflavin from the environment and are therefore absolutely dependent on endogenous synthesis of the vitamin. Riboflavin synthase is therefore a potential target for the development of antiinfective drugs.A cDNA sequence from Schizosaccharomyces pombe comprising a hypothetical open reading frame with similarity to riboflavin synthase of Escherichia coli was expressed in a recombinant E. coli strain. The recombinant protein is a homotrimer of 23 kDa subunits as shown by sedimentation equilibrium centrifugation. The protein sediments at an apparent velocity of 4.1 S at 20 degrees C. The amino acid sequence is characterized by internal sequence similarity indicating two similar folding domains per subunit. The enzyme catalyzes the formation of riboflavin from 6,7-dimethyl-8-ribityllumazine at a rate of 158 nmol mg(-1) min(-1) with an apparent KM of 5.7 microM. 19F NMR protein perturbation experiments using fluorine-substituted intermediate analogs show multiple signals indicating that a given ligand can be bound in at least 4 different states. 19F NMR signals of enzyme-bound intermediate analogs were assigned to ligands bound by the N-terminal respectively C-terminal folding domain on basis of NMR studies with mutant proteins.Riboflavin synthase of Schizosaccharomyces pombe is a trimer of identical 23-kDa subunits. The primary structure is characterized by considerable similarity of the C-terminal and N-terminal parts. Riboflavin synthase catalyzes a mechanistically complex dismutation of 6,7-dimethyl-8-ribityllumazine affording riboflavin and 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione. The 19F NMR data suggest large scale dynamic mobility in the trimeric protein which may play an important role in the reaction mechanism.
| S-EPMC337094 | biostudies-literature
Project description:In modern kinase drug discovery, allosteric inhibitors have become a focus of attention due to their potential selectivity, but such compounds are difficult to identify. Here we describe an NMR-based competition assay using 19F-containing reporter molecules, which allows for rapid identification and discrimination between ATP-competitive and allosteric kinase inhibitors. We illustrate the principle of such a dual-site competition assay with the example of catalytic and allosteric ABL1 kinase inhibitors. The assay can also be used to identify and characterize mixed binding modes of well-known drugs, as shown for crizotinib and fingolimod.
| S-EPMC5467191 | biostudies-literature
Project description:This SuperSeries is composed of the SubSeries listed below.
2018-06-08 | GSE107768 | GEO
Project description:Gene therapy has emerged as a promising strategy for treatment of various diseases. However, widespread implementation is hampered by difficulties in assessing the success of transfection in the target tissue and the longevity of gene expression. Thus, there is increasing interest in the development of non-invasive in vivo reporter techniques to assay gene expression. We recently demonstrated the ability to detect beta-galactosidase activity in stably transfected human prostate tumor xenografts in mice in vivo using 19F NMR. We now extend the studies to human MCF7 breast cancer cells growing as xenografts in nude mice. Moreover, by using two spectrally resolved reporters (o-fluoro-p-nitrophenyl-beta-D-galactopyranoside and an isomer), two tumors could be interrogated simultaneously revealing lacZ transgene activity in a stably transfected tumor versus no activity in a wild-type tumor. Most significantly, hydrolytic activity observed by 19F NMR corresponded to differential activity in lacZ-expressing tumors.
| S-EPMC3044929 | biostudies-other
Project description:19F solid-state NMR is an excellent approach for measuring long-range distances for structure determination and for studying molecular motion. For multi-fluorinated proteins, assignment of 19F chemical shifts has been traditionally carried out using mutagenesis. Here we show 2D 19F-13C correlation experiments that allow efficient assignment of the 19F chemical shifts. We have compared several rotational-echo double-resonance-based pulse sequences and 19F-13C cross polarization (CP) for 2D 19F-13C correlation. We found that direct transferred-echo double-resonance (TEDOR) transfer from 19F to 13C and vice versa outperforms out-and-back coherence transfer schemes. 19F detection gives twofold higher sensitivity over 13C detection for the 2D correlation experiment. At MAS frequencies of 25-35 kHz, double-quantum 19F-13C CP has higher coherence transfer efficiencies than zero-quantum CP. The most efficient TEDOR transfer experiment has higher sensitivity than the most efficient double-quantum CP experiment. We demonstrate these 2D 19F-13C correlation experiments on the model compounds t-Boc-4F-phenylalanine and GB1. Application of the 2D 19F-13C TEDOR correlation experiment to the tetrameric influenza BM2 transmembrane peptide shows intermolecular 13C-19F cross peaks that indicate that the BM2 tetramers cluster in the lipid bilayer in an antiparallel fashion. This clustering may be relevant for the virus budding function of this protein.
| S-EPMC7445029 | biostudies-literature
Project description:ADAPT-NMR (Assignment-directed Data collection Algorithm utilizing a Probabilistic Toolkit in NMR) is a software package whose Bayesian core uses on-the-fly chemical shift assignments to guide data acquisition by non-uniform sampling from a panel of through-bond NMR experiments. The new version of ADAPT-NMR (ADAPT-NMR v3.0) has the option of utilizing 2D tilted-plane versions of 3D fast spectral acquisition with BEST-type pulse sequences, while also retaining the capability of acquiring and processing data from tilted-plane versions of conventional sensitivity-enhanced experiments. The use of BEST experiments significantly reduces data collection times and leads to enhanced performance by ADAPT-NMR.
| S-EPMC4687732 | biostudies-literature
Project description:Internuclear distances measured using NMR provide crucial constraints of three-dimensional structures but are often restricted to about 5 Å due to the weakness of nuclear-spin dipolar couplings. For studying macromolecular assemblies in biology and materials science, distance constraints beyond 1 nm will be extremely valuable. Here we present an extensive and quantitative analysis of the feasibility of 19F spin exchange NMR for precise and robust measurements of interatomic distances up to 1.6 nm at a magnetic field of 14.1 T, under 20-40 kHz magic-angle spinning (MAS). The measured distances are comparable to those achievable from paramagnetic relaxation enhancement but have higher precision, which is better than ±1 Å for short distances and ±2 Å for long distances. For 19F spins with the same isotropic chemical shift but different anisotropic chemical shifts, intermediate MAS frequencies of 15-25 kHz without 1H irradiation accelerate spin exchange. For spectrally resolved 19F-19F spin exchange, 1H-19F dipolar recoupling significantly speeds up 19F-19F spin exchange. On the basis of data from five fluorinated synthetic, pharmaceutical, and biological compounds, we obtained two general curves for spin exchange between CF groups and between CF3 and CF groups. These curves allow 19F-19F distances to be extracted from the measured spin exchange rates after taking into account 19F chemical shifts. These results demonstrate the robustness of 19F spin exchange NMR for distance measurements in a wide range of biological and chemical systems.
| S-EPMC6312665 | biostudies-literature
Project description:Enhanced cross-linking immunoprecipitation (eCLIP) featuring a size-matched input control has been recently applied to profile the binding sites of more than one hundred RNA binding proteins (RBPs). However computational pipelines and quality control metrics needed to process CLIP data at scale have yet to be well defined. Here, we describe our ENCODE eCLIP processing pipeline (https://github.com/YeoLab/eclip), enabling users to go from raw reads to processed peaks that are enriched above paired input, reproducible across biological replicates, and can be directly compared against the public ENCODE eCLIP resource. In particular, we discuss processing steps designed to address common artifacts, including properly quantifying unique RNA fragments bound by both unique genomic- and repetitive element-mapped reads. Using manual quality annotation of 350 ENCODE eCLIP experiments, we develop metrics for quality assessment of eCLIP experiments prior to and after sequencing, including library yield, number of unique fragments in the library, total binding relative information, and biological reproducibility. In particular, we quantify the commonly believed linkage between depth of sequencing and peak discovery, and derive methods for estimating required sequencing depth based on pre-sequencing metrics. Finally we provide recommendations for the common question of integrating RBP binding information with RNA-seq to generate splicing maps representing the positional effect of binding on alternative splicing. These pipelines and QC metrics enable large-scale processing and analysis of eCLIP data, and will help to standardize rigorous analysis of RBP binding data.
2018-06-08 | GSE107767 | GEO
Project description:Enhanced cross-linking immunoprecipitation (eCLIP) featuring a size-matched input control has been recently applied to profile the binding sites of more than one hundred RNA binding proteins (RBPs). However computational pipelines and quality control metrics needed to process CLIP data at scale have yet to be well defined. Here, we describe our ENCODE eCLIP processing pipeline (https://github.com/YeoLab/eclip), enabling users to go from raw reads to processed peaks that are enriched above paired input, reproducible across biological replicates, and can be directly compared against the public ENCODE eCLIP resource. In particular, we discuss processing steps designed to address common artifacts, including properly quantifying unique RNA fragments bound by both unique genomic- and repetitive element-mapped reads. Using manual quality annotation of 350 ENCODE eCLIP experiments, we develop metrics for quality assessment of eCLIP experiments prior to and after sequencing, including library yield, number of unique fragments in the library, total binding relative information, and biological reproducibility. In particular, we quantify the commonly believed linkage between depth of sequencing and peak discovery, and derive methods for estimating required sequencing depth based on pre-sequencing metrics. Finally we provide recommendations for the common question of integrating RBP binding information with RNA-seq to generate splicing maps representing the positional effect of binding on alternative splicing. These pipelines and QC metrics enable large-scale processing and analysis of eCLIP data, and will help to standardize rigorous analysis of RBP binding data.
2018-06-08 | GSE107766 | GEO
Project description:Tryptophan, an essential amino acid, is metabolized into a variety of small molecules capable of impacting human physiology, and aberrant tryptophan metabolism has been linked to a number of diseases. There are three principal routes by which tryptophan is degraded, and thus methods for measuring metabolic flux through these pathways can be used to understand the factors that perturb tryptophan metabolism and potentially to measure disease biomarkers. Here, we describe a method utilizing 6-fluorotryptophan as a probe for detecting tryptophan metabolites in ex vivo tissue samples via 19F nuclear magnetic resonance. As a proof of concept, we demonstrate that 6-fluorotryptophan can be used to measure changes in tryptophan metabolism resulting from antibiotic-induced changes in gut microbiota composition. Taken together, we describe a general strategy for monitoring amino acid metabolism using 19F nuclear magnetic resonance that is operationally simple and does not require chromatographic separation of metabolites.
| S-EPMC7075705 | biostudies-literature