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Véronique Stoven

Publications and source records attributed to Véronique Stoven.

7 recordsLinked to original sources
PubMed2006

Three dimensional structure and implications for the catalytic mechanism of 6-phosphogluconolactonase from Trypanosoma brucei.

Enzymes from the pentose phosphate pathway (PPP) are potential drug targets for the development of new drugs against Trypanosoma brucei, the causative agent of African sleeping disease: for instance, the 6-phosphogluconate dehydrogenase is currently studied actively for such purposes. Structural and functional studies are necessary to better characterize the associated enzymes and compare them to their human homologues, in order to undertake structure-based drug design studies on such targets. In this context, the crystal structure of 6-phosphogluconolactonase (6PGL) from T. brucei, the second enzyme from PPP, was determined at 2.1 Angstroms resolution. Comparison of its sequence and structure to other related proteins in the 6PGL family with a known structure (Thermotoga maritima Tm6GPL 1PBT and Vibrio cholerae Vc6PGL (1Y89), which have not been discussed in print), or in the glucosamine-6-phosphate-deaminase family (hexameric Escherichia coli 1DEA and monomeric Bacillus subtilis 2BKV), allowed the identification of the 6PGL active site. In addition to the analysis of the crystal structure, 3D NMR interaction studies and docking experiments are reported here. Key residues involved in substrate binding or in catalysis were identified.

Amino Acid Sequence↗
PubMed2006

Determination of dihedral Psi angles in large proteins by combining NH(N)/C(alpha)H(alpha) dipole/dipole cross-correlation and chemical shifts.

We propose a strategy based on the combination of experimental NH(N)/C(alpha)H(alpha) dipole/dipole cross-correlated relaxation rates and chemical shift analysis for the determination of Psi torsion angles in proteins. The method allows the determination of a dihedral angle that is not easily accessible by nuclear magnetic resonance (NMR). The measurement of dihedral angle restraints can be used for structure calculation, which is known to improve the quality of NMR structures. The method is of particular interest in the case of large proteins, for which spectral assignment of the nuclear Overhauser effect spectra, and therefore straightforward structural determination, is out of reach. One advantage of the method is that it is reasonably simple to implement, and could be used in association with other methods aiming at obtaining structural information on complex systems, such as residual dipolar coupling measurements. An illustrative example is analyzed in the case of the 30-kDa protein 6-phosphogluconolactonase.

Animals↗
PubMed2003

Biochemical characterization and NMR studies of the nucleotide-binding domain 1 of multidrug-resistance-associated protein 1: evidence for interaction between ATP and Trp653.

Multidrug-resistance-associated protein 1 (MRP1/ABCC1) is a human ATP-binding cassette transporter that confers cell resistance to antitumour drugs. Its NBDs (nucleotide-binding domains) bind/hydrolyse ATP, a key step in the activation of MRP1 function. To relate its intrinsic functional features to the mechanism of action of the full-size transporter, we expressed the N-terminal NBD1 domain (Asn(642) to Ser(871)) in Escherichia coli. NBD1 was highly purified under native conditions and was characterized as a soluble monomer. (15)N-labelling allowed recording of the first two-dimensional NMR spectra of this domain. The NMR study showed that NBD1 was folded, and that Trp(653) was a key residue in the NBD1-ATP interaction. Thus, interaction of NBD1 with ATP/ADP was studied by intrinsic tryptophan fluorescence. The affinity for ATP and ADP were in the same range (K (d(ATP))=118 microM and K (d(ADP))=139 microM). Binding of nucleotides did not influence the monomeric state of NBD1. The ATPase activity of NBD1 was magnesium-dependent and very low [V (max) and K (m) values of 5x10(-5) pmol of ATP x (pmol NBD1)(-1) x s(-1) and 833 microM ATP respectively]. The present study suggests that NBD1 has a low contribution to the ATPase activity of full-length MRP1 and/or that this activity requires NBD1-NBD2 heterodimer formation.

Adenosine Diphosphate↗
PubMed2003

An insight into the role of human pancreatic lithostathine.

Human lithostathine was initially isolated from pancreatic stones in patients with alcoholic calcifying chronic pancreatitis. It is secreted into the pancreatic juice where it was believed to inhibit stone formation. The N-terminal undecapeptide was assumed to play an important role in the mechanism, by adsorption to the crystal surface. Later, the role of lithostathine in calcite formation and growth was questioned, together with the associated mechanism of action. In particular, although lithostathine adsorbs on calcite crystal, this property does not now seem to be specific. Moreover, the N-terminal undecapeptide is not likely to have, by itself, the function of the entire protein. The different aspects of this controversy are reviewed and discussed, particularly in the light of recent structural biology. Comparative biological data now available allow us to draw an interesting parallel between lithostathine and other related proteins. Finally, lithostathine might affect stone formation and may also have another function which could be investigated in the other proteins belonging to the same structural family.

Amino Acid Sequence↗
PubMed2002

Glutathione levels and BAX activation during apoptosis due to oxidative stress in cells expressing wild-type and mutant cystic fibrosis transmembrane conductance regulator.

Cystic fibrosis is characterized by chronic inflammation and an imbalance in the concentrations of alveolar and lung oxidants and antioxidants, which result in cell damage. Modifications in lung glutathione concentrations are recognized as a salient feature of inflammatory lung diseases such as cystic fibrosis, and glutathione plays a major role in protection against oxidative stress and is important in modulation of apoptosis. The cystic fibrosis transmembrane conductance regulator (CFTR) is permeable to Cl(-), larger organic ions, and reduced and oxidized forms of glutathione, and the DeltaF508 CFTR mutation found in cystic fibrosis patients has been correlated with impaired glutathione transport in cystic fibrosis airway epithelia. Because intracellular glutathione protects against oxidative stress-induced apoptosis, we studied the susceptibility of epithelial cells (HeLa and IB3-1) expressing normal and mutant CFTR to apoptosis triggered by H(2)O(2). We find that cells with normal CFTR are more sensitive to oxidative stress-induced apoptosis than cells expressing defective CFTR. In addition, sensitivity to apoptosis could be correlated with glutathione levels, because depletion of intracellular glutathione results in higher levels of apoptosis, and glutathione levels decreased faster in cells expressing normal CFTR than in cells with defective CFTR during incubation with H(2)O(2). The pro-apoptotic BCL-2 family member, BAX, is also activated faster in cells expressing normal CFTR than in those with mutant CFTR under these conditions, and artificial glutathione depletion increases the extent of BAX activation. These results suggest that glutathione-dependent BAX activation in cells with normal CFTR represents an early step in oxidative stress-induced apoptosis of these cells.

Amino Acid Substitution↗
PubMedDate not supplied

The pharmacophore kernel for virtual screening with support vector machines.

We introduce a family of positive definite kernels specifically optimized for the manipulation of 3D structures of molecules with kernel methods. The kernels are based on the comparison of the three-point pharmacophores present in the 3D structures of molecules, a set of molecular features known to be particularly relevant for virtual screening applications. We present a computationally demanding exact implementation of these kernels, as well as fast approximations related to the classical fingerprint-based approaches. Experimental results suggest that this new approach is competitive with state-of-the-art algorithms based on the 2D structure of molecules for the detection of inhibitors of several drug targets.

Algorithms↗