scholarly journals Crystal structure of the active form of native human thymidylate synthase in the absence of bound substrates

2017 ◽  
Vol 73 (6) ◽  
pp. 336-341 ◽  
Author(s):  
P. Deschamps ◽  
S. Réty ◽  
J. Bareille ◽  
N. Leulliot
Keyword(s):  
Thymidylate Synthase ◽  
Active Site ◽  
De Novo ◽  
Active Form ◽  
Amino Acid Residues ◽  
Active Conformation ◽  
Sulfate Ions ◽  
Inactive Conformation ◽  
Anticancer Chemotherapy ◽  
Catalytic Loop

Human thymidylate synthase (hTS) provides the solede novointracellular source of thymidine 5′-monophosphate (dTMP). hTS is required for DNA replication prior to cell division, making it an attractive target for anticancer chemotherapy and drug discovery. hTS binds 2′-deoxyuridine 5′-monophosphate (dUMP) and the folate co-substrateN5,N10-methylenetetrahydrofolate (meTHF) in a pocket near the catalytic residue Cys195. The catalytic loop, which is composed of amino-acid residues 181–197, can adopt two distinct conformations related by a 180° rotation. In the active conformation Cys195 is close to the active site, while in the inactive conformation it is rotated and Cys195 is too distant from the active site for catalysis. Several hTS structures, either native or engineered, have been solved in the active conformation in complex with ligands or inhibitors and at different salt concentrations. However, apo hTS structures have been solved in an inactive conformation in high-salt and low-salt conditions (PDB entries 1ypv, 4h1i, 4gyh, 3egy and 3ehi). Here, the structure of apo hTS crystallized in the active form with sulfate ions coordinated by the arginine residue that binds dUMP is reported.

scholarly journals Myricetin allosterically inhibits Dengue NS2B-NS3 protease as studied by NMR and MD simulations

2021 ◽  
Author(s):  
Mei Dang ◽  
Jianxing Song
Keyword(s):  
Active Site ◽  
Active Form ◽  
Md Simulations ◽  
Active Conformation ◽  
Allosteric Site ◽  
Allosteric Inhibition ◽  
Inactive Conformation ◽  
Active Site Pocket ◽  
Nmr Study ◽  
Ns3 Protease

Dengue NS2B-NS3 protease existing in equilibrium between the active and inactive forms is essential for virus replication, thus representing a key drug target. Here Myricetin, a plant flavonoid, was characterized to non-competitively inhibit Dengue protease. Further NMR study identified the protease residues perturbed by binding to Myricetin, which were utilized to construct the Myricetin-protease complexes. Strikingly, in the active form Myricetin binds a new allosteric site (AS2) far away from the active site pocket and allosteric site (AS1) for binding Curcumin, while in the inactive form it binds both AS1 and AS2. To decipher the mechanism for the allosteric inhibition by Myricetin, we conducted molecular dynamics (MD) simulations on different forms of Dengue NS2B-NS3 protease. Unexpectedly, the binding of Myricetin to AS2 is sufficient to disrupt the active conformation by displacing the characteristic NS2B C-terminal b- hairpin from the active site pocket. By contrast, the binding of Myricetin to AS1 and AS2 results in locking the inactive conformation. Therefore Myricetin represents the first small molecule which allosterically inhibits Dengue protease by both disrupting the active conformation and locking the inactive conformation. The results enforce the notion that a global allosteric network exists in Dengue NS2B-NS3 protease, which is susceptible to allosteric inhibition by small molecules such as Myricetin and Curcumin. As Myricetin has been extensively used as a food additive, it might be directly utilized to fight the Dengue infections and as a promising starting for further design of potent allosteric inhibitors.

scholarly journals An enzymatic activation of formaldehyde for nucleotide methylation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Charles Bou-Nader ◽  
Frederick W. Stull ◽  
Ludovic Pecqueur ◽  
Philippe Simon ◽  
Vincent Guérineau ◽  
...  
Keyword(s):  
Amino Acids ◽  
Thymidylate Synthase ◽  
Active Site ◽  
De Novo ◽  
Crystallographic Structure ◽  
De Novo Synthesis ◽  
Active Site Residues ◽  
Enzymatic Activation ◽  
Enzyme Cofactors ◽  
Unique Ability

AbstractFolate enzyme cofactors and their derivatives have the unique ability to provide a single carbon unit at different oxidation levels for the de novo synthesis of amino-acids, purines, or thymidylate, an essential DNA nucleotide. How these cofactors mediate methylene transfer is not fully settled yet, particularly with regard to how the methylene is transferred to the methylene acceptor. Here, we uncovered that the bacterial thymidylate synthase ThyX, which relies on both folate and flavin for activity, can also use a formaldehyde-shunt to directly synthesize thymidylate. Combining biochemical, spectroscopic and anaerobic crystallographic analyses, we showed that formaldehyde reacts with the reduced flavin coenzyme to form a carbinolamine intermediate used by ThyX for dUMP methylation. The crystallographic structure of this intermediate reveals how ThyX activates formaldehyde and uses it, with the assistance of active site residues, to methylate dUMP. Our results reveal that carbinolamine species promote methylene transfer and suggest that the use of a CH2O-shunt may be relevant in several other important folate-dependent reactions.

scholarly journals Structural and Functional Characterization of the Human Thymidylate Synthase (hTS) Interface Variant R175C, New Perspectives for the Development of hTS Inhibitors

Molecules ◽  
2019 ◽  
Vol 24 (7) ◽  
pp. 1362
Author(s):  
Cecilia Pozzi ◽  
Stefania Ferrari ◽  
Rosaria Luciani ◽  
Maria Costi ◽  
Stefano Mangani
Keyword(s):  
Thymidylate Synthase ◽  
Active Site ◽  
Functional Characterization ◽  
Binding Mode ◽  
Anticancer Chemotherapy ◽  
Innovative Strategies ◽  
X Ray Crystallography ◽  
Site Targeting ◽  
New Strategies

Human thymidylate synthase (hTS) is pivotal for cell survival and proliferation, indeed it provides the only synthetic source of dTMP, required for DNA biosynthesis. hTS represents a validated target for anticancer chemotherapy. However, active site-targeting drugs towards hTS have limitations connected to the onset of resistance. Thus, new strategies have to be applied to effectively target hTS without inducing resistance in cancer cells. Here, we report the generation and the functional and structural characterization of a new hTS interface variant in which Arg175 is replaced by a cysteine. Arg175 is located at the interface of the hTS obligate homodimer and protrudes inside the active site of the partner subunit, in which it provides a fundamental contribution for substrate binding. Indeed, the R175C variant results catalytically inactive. The introduction of a cysteine at the dimer interface is functional for development of new hTS inhibitors through innovative strategies, such as the tethering approach. Structural analysis, performed through X-ray crystallography, has revealed that a cofactor derivative is entrapped inside the catalytic cavity of the hTS R175C variant. The peculiar binding mode of the cofactor analogue suggests new clues exploitable for the design of new hTS inhibitors.

scholarly journals Cloning and expression of a human choline/ethanolaminephosphotransferase: synthesis of phosphatidylcholine and phosphatidylethanolamine

1999 ◽  
Vol 339 (2) ◽  
pp. 291-298 ◽  
Author(s):  
Annette L. HENNEBERRY ◽  
Christopher R. McMASTER
Keyword(s):  
De Novo ◽  
Active Form ◽  
Fatty Acyl ◽  
Cloning And Expression ◽  
Amino Acid Residues ◽  
Reading Frame ◽  
Kennedy Pathway ◽  
Membrane Spanning

Cholinephosphotransferase catalyses the final step in the synthesis of phosphatidylcholine (PtdCho) via the Kennedy pathway by the transfer of phosphocholine from CDP-choline to diacylglycerol. Ethanolaminephosphotransferase catalyses an analogous reaction with CDP-ethanolamine as the phosphobase donor for the synthesis of phosphatidylethanolamine (PtdEtn). Together these two enzyme activities determine both the site of synthesis and the fatty acyl composition of PtdCho and PtdEtn synthesized de novo. A human choline/ethanolaminephosphotransferase cDNA (hCEPT1) was cloned, expressed and characterized. Northern blot analysis revealed one hCEPT1 2.3 kb transcript that was ubiquitous and not enriched, with respect to actin, in any particular cell type. The open reading frame predicts a protein (hCEPT1p) of 416 amino acid residues with a molecular mass of 46550 Da containing seven membrane-spanning domains. A predicted amphipathic helix resides within the active site of the enzyme with the final two aspartic residues of the CDP-alcohol phosphotransferase motif, DG(X)2AR(X)8G(X)3D(X)3D, positioned within this helix. hCEPT1p was successfully expressed in a full-length, active form in Saccharomyces cerevisiae cells devoid of endogenous cholinephosphotransferase or ethanolaminephosphotransferase activities (HJ091, cpt1::LEU2 ept1-). In vitro, hCEPT1p displayed broad substrate specificity, utilizing both CDP-choline and CDP-ethanolamine as phosphobase donors to a broad range of diacylglycerols, resulting in the synthesis of both PtdCho and PtdEtn. In vivo, S. cerevisiae cells (HJ091, cpt1::LEU2 ept1-) expressing hCEPT1 efficiently incorporated both radiolabelled choline and ethanolamine into phospholipids, demonstrating that hCEPT1p has the ability to synthesize both choline- and ethanolamine- containing phospholipids in vitro and in vivo.

scholarly journals Crystal structure of recombinant phosphoribosylpyrophosphate synthetase 2 fromThermus thermophilusHB27 complexed with ADP and sulfate ions

2017 ◽  
Vol 73 (6) ◽  
pp. 369-375 ◽  
Author(s):  
Vladimir I. Timofeev ◽  
Ekaterina V. Sinitsyna ◽  
Maria A. Kostromina ◽  
Tatiana I. Muravieva ◽  
Dmitry A. Makarov ◽  
...  
Keyword(s):  
Active Site ◽  
Thermus Thermophilus ◽  
Three Dimensional ◽  
Class I ◽  
Dimensional Structure ◽  
Sulfate Ions ◽  
Atp Binding Site ◽  
Allosteric Sites ◽  
Catalytic Loop ◽  
Phosphoribosylpyrophosphate Synthetase

Phosphoribosylpyrophosphate synthetase (PRPPS) from the thermophilic bacterial strainThermus thermophilusHB27 catalyzes the synthesis of phosphoribosylpyrophosphate from ribose 5-phosphate and ATP, and belongs to the class I PRPPSs. The three-dimensional structure of the recombinant enzyme was solved at 2.2 Å resolution using crystals grown in microgravity from protein solution containing ATP, magnesium and sulfate ions. An ADP molecule was located in the active site of each subunit of the hexameric enzyme molecule and sulfate ions were located in both the active and allosteric sites. It was found that the catalytic loop that restricts the active-site area and is usually missing from the electron-density map of class I PRPPSs adopts different conformations in three independent subunits inT. thermophilusPRPPS. A closed conformation of the active site was found in one of subunits where the highly ordered catalytic β-hairpin delivers the Lys and Arg residues that are essential for activity directly to the ADP molecule, which occupies the ATP-binding site. A comparison of the conformations of the catalytic loop in the three independent subunits reveals a possible mode of transition from the open to the closed state of the active site during the course of the catalyzed reaction.

scholarly journals Mechanistic and structural basis for inhibition of thymidylate synthase ThyX

Open Biology ◽  
2012 ◽  
Vol 2 (10) ◽  
pp. 120120 ◽  
Author(s):  
Tamara Basta ◽  
Yap Boum ◽  
Julien Briffotaux ◽  
Hubert F. Becker ◽  
Isabelle Lamarre-Jouenne ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Thymidylate Synthase ◽  
Active Site ◽  
De Novo ◽  
Tight Binding ◽  
Binding Pocket ◽  
Structural Basis ◽  
Microbial Genomes ◽  
Thymidylate Synthases ◽  
Thymidylate Synthesis

Nature has established two mechanistically and structurally unrelated families of thymidylate synthases that produce de novo thymidylate or dTMP, an essential DNA precursor. Representatives of the alternative flavin-dependent thymidylate synthase family, ThyX, are found in a large number of microbial genomes, but are absent in humans. We have exploited the nucleotide binding pocket of ThyX proteins to identify non-substrate-based tight-binding ThyX inhibitors that inhibited growth of genetically modified Escherichia coli cells dependent on thyX in a manner mimicking a genetic knockout of thymidylate synthase. We also solved the crystal structure of a viral ThyX bound to 2-hydroxy-3-(4-methoxybenzyl)-1,4-naphthoquinone at a resolution of 2.6 Å. This inhibitor was found to bind within the conserved active site of the tetrameric ThyX enzyme, at the interface of two monomers, partially overlapping with the dUMP binding pocket. Our studies provide new chemical tools for investigating the ThyX reaction mechanism and establish a novel mechanistic and structural basis for inhibition of thymidylate synthesis. As essential ThyX proteins are found e.g. in Mycobacterium tuberculosis and Helicobacter pylori , our studies have also potential to pave the way towards the development of new anti-microbial compounds.

scholarly journals Redox Properties of Human Medium-Chain Acyl-CoA Dehydrogenase, Modulation by Charged Active-Site Amino Acid Residues†

Biochemistry ◽  
1998 ◽  
Vol 37 (41) ◽  
pp. 14605-14612 ◽  
Author(s):  
Gina J. Mancini-Samuelson ◽  
Volker Kieweg ◽  
Kim Marie Sabaj ◽  
Sandro Ghisla ◽  
Marian T. Stankovich
Keyword(s):  
Amino Acid ◽  
Active Site ◽  
Redox Properties ◽  
Amino Acid Residues ◽  
Medium Chain ◽  
Chain Acyl

scholarly journals Identification of NAD+ Synthetase from Streptococcus sobrinus as a B-Cell-Stimulatory Protein

2004 ◽  
Vol 186 (2) ◽  
pp. 419-426 ◽  
Author(s):  
Isabel Veiga-Malta ◽  
Margarida Duarte ◽  
Márcia Dinis ◽  
Pedro Madureira ◽  
Paula Ferreira ◽  
...  
Keyword(s):  
B Cell ◽  
Active Form ◽  
Lymphocyte Activation ◽  
Amino Acid Residues ◽  
Streptococcus Sobrinus ◽  
Reading Frame ◽  
High Sequence Homology ◽  
Culture Supernatants ◽  
Nad Synthetase

ABSTRACT Streptococcus sobrinus, one agent of dental caries, secretes a protein that induces lymphocyte polyclonal activation of the host as a mechanism of immune evasion. We have isolated from culture supernatants of this bacterium a protein with murine B-cell-stimulatory properties and subsequently cloned the relevant gene. It contains an open reading frame of 825 bp encoding a polypeptide with 275 amino acid residues and a molecular mass of 30 kDa. The protein displays high sequence homology with NAD+ synthetases from several organisms, including a conserved fingerprint sequence (SGGXD) characteristic of ATP pyrophosphatases. The polypeptide was expressed in Escherichia coli as a hexahistidine-tagged protein and purified in an enzymatically active form. The recombinant NAD+ synthetase stimulates murine B cells after in vitro treatment of spleen cell cultures, as demonstrated by its ability to induce up-regulation of the expression of CD69, an early marker of lymphocyte activation. Stimulation with the recombinant NAD+ synthetase was also observed with other B-cell markers, such as CD19+, B220+, and CD21+. Cell proliferation follows the activation induced by the recombinant NAD+ synthetase.

scholarly journals Distinct Subregions of Swi1 Manifest Striking Differences in Prion Transmission and SWI/SNF Function

2010 ◽  
Vol 30 (19) ◽  
pp. 4644-4655 ◽  
Author(s):  
Zhiqiang Du ◽  
Emily T. Crow ◽  
Hyun Seok Kang ◽  
Liming Li
Keyword(s):  
Chromatin Remodeling ◽  
De Novo ◽  
Amino Acid Residues ◽  
Coding Region ◽  
Conformational Switch ◽  
Amyloid Fibers ◽  
Aggregation Pattern ◽  
Prion Transmission ◽  
Shed Light

ABSTRACT We have recently reported that the yeast chromatin-remodeling factor Swi1 can exist as a prion, [SWI +], demonstrating a link between prionogenesis and global transcriptional regulation. To shed light on how the Swi1 conformational switch influences Swi1 function and to define the sequence and structural requirements for [SWI +] formation and propagation, we functionally dissected the Swi1 molecule. We show here that the [SWI +] prion features are solely attributable to the first 327 amino acid residues (N), a region that is asparagine rich. N was aggregated in [SWI+ ] cells but diffuse in [swi− ] cells; chromosomal deletion of the N-coding region resulted in [SWI +] loss, and recombinant N peptide was able to form infectious amyloid fibers in vitro, enabling [SWI +] de novo formation through a simple transformation. Although the glutamine-rich middle region (Q) was not sufficient to aggregate in [SWI +] cells or essential for SWI/SNF function, it significantly modified the Swi1 aggregation pattern and Swi1 function. We also show that excessive Swi1 incurred Li+/Na+ sensitivity and that the N/Q regions are important for this gain of sensitivity. Taken together, our results provide the final proof of “protein-only” transmission of [SWI +] and demonstrate that the widely distributed “dispensable” glutamine/asparagine-rich regions/motifs might have important and divergent biological functions.

Sign in / Sign up

Export Citation Format

Share Document