A5059317272- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Enzyme Structure and Function
- DNA and Nucleic Acid Chemistry
- RNA and protein synthesis mechanisms
- Protein Structure and Dynamics
- RNA Interference and Gene Delivery
- Advanced biosensing and bioanalysis techniques
- Biochemical and Molecular Research
- RNA modifications and cancer
- Genomics and Chromatin Dynamics
- DNA Repair Mechanisms
- Neuroscience and Neuropharmacology Research
- Epigenetics and DNA Methylation
- Cancer-related gene regulation
- Redox biology and oxidative stress
- Crystallography and molecular interactions
- Carbohydrate Chemistry and Synthesis
- Radiopharmaceutical Chemistry and Applications
- HIV/AIDS drug development and treatment
- Receptor Mechanisms and Signaling
- Glutathione Transferases and Polymorphisms
- Peptidase Inhibition and Analysis
- Phytase and its Applications
- Bacterial Genetics and Biotechnology
Vanderbilt University
2015-2024
Vanderbilt University Medical Center
2013-2021
Université d'Évry Val-d'Essonne
2012
National Institute of Standards and Technology
2007
Biotechnology Institute
2007
Wake Forest University
2005
Massachusetts Institute of Technology
2005
Argonne National Laboratory
2005
Oak Ridge National Laboratory
1986-2004
University of Tennessee at Knoxville
1986-2004
The preferential in vitro methylation of histone H3 by coactivator-associated arginine methyltransferase 1 (CARM1) has been proposed as a basis for its ability to enhance gene transcription [Chen, D., et al. (1999) Science 284, 2174−2177]. To further evaluate the significance methylation, we studied kinetics and site specificity modification CARM1. Affinity-purified CARM1 methylated recombinant chick H3, which is free posttranslational modifications, calf thymus heterogeneous with regard...
The 2.5 Å X-ray crystal structure of the nucleosome core particle presented here provides significant additions to understanding nucleosome, fundamental unit chromatin structure. Extensions are made N-terminal histone tails and details provided on hydration ion binding. is composed twofold symmetric molecules, native chicken octamer cores DNA palindrome, which were expected form a perfectly particle. In fact, result asymmetric owing binding protein surface packing particles in lattice. An...
Naproxen ((S)-6-methoxy-α-methyl-2-naphthaleneacetic acid) is a powerful non-selective non-steroidal anti-inflammatory drug that extensively used as prescription and over-the-counter medication. exhibits gastrointestinal toxicity, but its cardiovascular toxicity may be reduced compared with other drugs in class. Despite the fact naproxen has been marketed for many years, molecular basis of interaction cyclooxygenase (COX) enzymes unknown. We performed detailed study naproxen-COX-2...
Sterol 14alpha-demethylase (14DM, the CYP51 family of cytochrome P450) is an essential enzyme in sterol biosynthesis eukaryotes. It serves as a major drug target for fungal diseases and can potentially become treatment human infections with protozoa. Here we present 1.9 A resolution crystal structures 14DM from protozoan pathogen Trypanosoma brucei, ligand-free complexed strong chemically selected inhibitor...
Here we report the investigation of glycol nucleic acid (GNA), an acyclic analogue, as a modification siRNA duplexes. We evaluated impact (S)- or (R)-GNA nucleotide incorporation on RNA duplex structure by determining three individual crystal structures. These structures indicate that (S)-nucleotide backbone adopts conformation has little overall structure, while (R)-nucleotide disrupts phosphate and hydrogen bonding adjacent base pair. In addition, GNA-T nucleobase rotated in which 5-methyl...
Chemical modifications are necessary to ensure the metabolic stability and efficacy of oligonucleotide-based therapeutics. Here, we describe analyses α-(l)-threofuranosyl nucleic acid (TNA) modification, which has a shorter 3'-2' internucleotide linkage than natural DNA RNA, in context small interfering RNAs (siRNAs). The TNA modification enhanced nuclease resistance more 2'-O-methyl or 2'-fluoro ribose modifications. TNA-containing siRNAs were prepared as triantennary N-acetylgalactosamine...
A functional high throughput screen and subsequent multidimensional, iterative parallel synthesis effort identified the first muscarinic acetylcholine receptor (mAChR) negative allosteric modulator (NAM) selective for M5 subtype. ML375 is a highly NAM with submicromolar potency (human IC50 = 300 nM, rat 790 M1–M4 > 30 μM), excellent multispecies PK, CNS penetration, enantiospecific inhibition.
We designed novel 4′-modified 2′-deoxy-2′-fluorouridine (2′-F U) analogues with the aim to improve nuclease resistance and potency of therapeutic siRNAs by introducing 4′-C-methoxy (4′-OMe) as alpha (C4′α) or beta (C4′β) epimers. The C4′α epimer was synthesized a stereoselective route in six steps; however, both α β epimers could be obtained nonstereoselective approach starting from 2′-F U. 1H NMR analysis computational investigation α-epimer revealed that 4′-OMe imparts conformational bias...
Selective activation of the M1 subtype muscarinic acetylcholine receptor, via positive allosteric modulation (PAM), is an exciting strategy to improve cognition in schizophrenia and Alzheimer's disease patients. However, highly potent ago-PAMs, such as MK-7622, PF-06764427, PF-06827443, can engender excessive M1, leading agonist actions prefrontal cortex (PFC) that impair cognitive function, induce behavioral convulsions, result other classic cholinergic adverse events (AEs). Here, we report...
Although cryogenic data collection has become the method of choice for macromolecular crystallography, flash-cooling step can dramatically increase mosaicity some crystals. Macromolecular crystal annealing significantly reduces flash-cooled crystals without affecting molecular structure. The process, which cycles a to ambient temperature and back temperature, is simple, quick requires no special equipment. process been applied several different macromolecules grown from precipitants using...
Focused library synthesis and structure–activity relationship development of 5,6,7-substituted pyrazolopyrimidines led to the discovery 2-(5,7-diethyl-2-(4-(2-fluoroethoxy)phenyl)pyrazolo[1,5-a]pyrimidin-3-yl)-N,N-diethylacetamide (6b), a novel translocator protein (TSPO) ligand exhibiting 36-fold enhancement in affinity compared another pyrazolopyrimidine-based TSPO ligand, 6a (DPA-714). Radiolabeling with fluorine-18 (18F) facilitated production...
The Gram-positive pathogen Staphylococcus aureus is a leading cause of global morbidity and mortality. Like many multi-drug-resistant organisms, S. contains antibiotic-modifying enzymes that facilitate resistance to multitude antimicrobial compounds. FosB Mn(2+)-dependent fosfomycin-inactivating enzyme found in catalyzes nucleophilic addition either l-cysteine (l-Cys) or bacillithiol (BSH) the antibiotic, resulting modified compound with no bactericidal properties. three-dimensional X-ray...
The fosfomycin resistance enzymes, FosB, from Gram-positive organisms, are M(2+)-dependent thiol tranferases that catalyze nucleophilic addition of either L-cysteine (L-Cys) or bacillithiol (BSH) to the antibiotic, resulting in a modified compound with no bacteriacidal properties. Here we report structural and functional characterization FosB Bacillus cereus (FosB(Bc)). overall structure FosB(Bc), at 1.27 Å resolution, reveals enzyme belongs vicinal oxygen chelate (VOC) superfamily. Crystal...
Although judicious use of chemical modifications has contributed to the success nucleic acid therapeutics, poor systemic stability remains a major hurdle. The introduction functional groups around phosphate backbone can enhance nuclease resistance oligonucleotides (ONs). Here, we report synthesis enantiomerically pure (R)- and (S)-5′-C-methyl (C5′-Me) substituted nucleosides their incorporation into ONs. These generally resulted in decrease thermal oligonucleotide (ON) duplexes manner...
In this report, we investigated the hexopyranose chemical modification Altriol Nucleic Acid (ANA) within small interfering RNA (siRNA) duplexes that were otherwise fully modified with 2'-deoxy-2'-fluoro and 2'-O-methyl pentofuranose modifications. The siRNAs designed to silence transthyretin (Ttr) gene conjugated a trivalent N-acetylgalactosamine (GalNAc) ligand for targeted delivery hepatocytes. Sense antisense strands of parent duplex synthesized single ANA residues at each position on...
To understand the role of structural elements RNA pseudoknots in controlling extent -1-type ribosomal frameshifting, we determined crystal structure a high-efficiency frameshifting mutant pseudoknot from potato leaf roll virus (PLRV). Correlations with available vitro data for PLRV mutants implicate sequence and length stem-loop linker as modulators efficiency. Although sequences overall structures beet western yellow (BWYV) are similar, nucleotide deletions adjacent minor groove loop...
Chemical modification is a prerequisite of oligonucleotide therapeutics for improved metabolic stability, uptake and activity, irrespective their mode action, i.e. antisense, RNAi or aptamer. Phosphate moiety ribose C2'/O2' atoms are the most common sites modification. Compared to 2'-O-substituents, 4'-C-substituents lie in proximity both 3'- 5'-adjacent phosphates. To investigate potentially beneficial effects on nuclease resistance we combined 2'-F 2'-OMe with 4'-Cα- 4'-Cβ-OMe,...
Abstract The N-(2-deoxy-d-erythro-pentofuranosyl)-urea DNA lesion forms following hydrolytic fragmentation of cis-5R,6S- and trans-5R,6R-dihydroxy-5,6-dihydrothymidine (thymine glycol, Tg) or from oxidation 7,8-dihydro-8-oxo-deoxyguanosine (8-oxodG) subsequent hydrolysis. It interconverts between α β deoxyribose anomers. Synthetic oligodeoxynucleotides containing this adduct are efficiently incised by unedited (K242) edited (R242) the hNEIL1 glycosylase. structure a complex active site...
It has been demonstrated previously that symmetric, homodimeric proteins are energetically favored, which explains their abundance in nature. proposed such symmetric homodimers underwent gene duplication and fusion to evolve into protein topologies have a arrangement of secondary structure elements--"symmetric superfolds". Here, the ROSETTA design software was used computationally engineer perfectly variant imidazole glycerol phosphate synthase its corresponding homodimer. The new protein,...
The crystal structure (1.50 Å resolution) and biochemical properties of the GSH transferase homologue, YghU, from Escherichia coli reveal that protein is unusual in it binds two molecules each active site. crystallographic observation consistent with biphasic equilibrium binding data indicate one tight (K(d1) = 0.07 ± 0.03 mM) weak (K(d2) 1.3 0.2 site for GSH. YghU exhibits little or no activity most typical electrophilic substrates but does possess a modest catalytic toward several organic...