Laboratoire de Biochimie Théorique
Présentation
The Laboratory of Theoretical Biochemistry (LBT) is one of five laboratories within Institut de Biologie Physico-Chimique (IBPC) in Paris.
LBT belongs to the French national research agency CNRS through its Institute of Chemistry, and is associated with Paris Diderot University. The laboratory was created at IBPC in 1958 as Laboratoire de Biochimie Théorique. Our field is theoretical and computational biochemistry, at the interface between biology, chemistry, physics, and computing.
Our strategic objectives are twofold: invent simulation algorithms to reproduce and predict physical properties of biomolecules either in vitro or in the cell, and understand the molecular or conformational factors responsible for the biological functions of living systems, and diseases. The equilibrium between these two aspects is the key point of the laboratory policy.
LBT is organized as a team of independent researchers with complementary interests and domains of expertise, both in method development and in biophysical, biochemical, and biomedical applications. Advances in each of these domains emerge from the association of different sets of researchers around individual projects.
Thèmes de recherche
Les axes de recherches du LBT se concentrent sur les développements méthodologiques et algorithmiques pour l’étude de la structure, la dynamique, la mécanique et les interactions des macromolécules biologiques.
Les objectifs sont donc d'utiliser les ordinateurs pour ouvrir des fenêtres vers le monde moléculaire, en aidant à comprendre les facteurs qui sous-tendent des faits expérimentaux, et en prédisant les propriétés et le comportement des molécules biologiques.
Equipes de recherche
Directeur : Marc Baaden
[inserm-00713313] Complex molecular assemblies at hand via interactive simulations.
Date: 29 juin 2012 - 19:34
Desc: Studying complex molecular assemblies interactively is becoming an increasingly appealing approach to molecular modeling. Here we focus on interactive molecular dynamics (IMD) as a textbook example for interactive simulation methods. Such simulations can be useful in exploring and generating hypotheses about the structural and mechanical aspects of biomolecular interactions. For the first time, we carry out low-resolution coarse-grain IMD simulations. Such simplified modeling methods currently appear to be more suitable for interactive experiments and represent a well-balanced compromise between an important gain in computational speed versus a moderate loss in modeling accuracy compared to higher resolution all-atom simulations. This is particularly useful for initial exploration and hypothesis development for rare molecular interaction events. We evaluate which applications are currently feasible using molecular assemblies from 1900 to over 300,000 particles. Three biochemical systems are discussed: the guanylate kinase (GK) enzyme, the outer membrane protease T and the soluble N-ethylmaleimide-sensitive factor attachment protein receptors complex involved in membrane fusion. We induce large conformational changes, carry out interactive docking experiments, probe lipid-protein interactions and are able to sense the mechanical properties of a molecular model. Furthermore, such interactive simulations facilitate exploration of modeling parameters for method improvement. For the purpose of these simulations, we have developed a freely available software library called MDDriver. It uses the IMD protocol from NAMD and facilitates the implementation and application of interactive simulations. With MDDriver it becomes very easy to render any particle-based molecular simulation engine interactive. Here we use its implementation in the Gromacs software as an example.
[hal-01523850] Determinants of neuroglobin plasticity highlighted by joint coarse-grained simulations and high pressure crystallography.
Date: 17 mai 2017 - 10:59
Desc: Investigating the effect of pressure sheds light on the dynamics and plasticity of proteins, intrinsically correlated to functional efficiency. Here we detail the structural response to pressure of neuroglobin (Ngb), a hexacoordinate globin likely to be involved in neuroprotection. In murine Ngb, reversible coordination is achieved by repositioning the heme more deeply into a large internal cavity, the “heme sliding mechanism”. Combining high pressure crystallography and coarse-grain simulations on wild type Ngb as well as two mutants, one (V101F) with unaffected and another (F106W) with decreased affinity for CO, we show that Ngb hinges around a rigid mechanical nucleus of five hydrophobic residues (V68, I72, V109, L113, Y137) during its conformational transition induced by gaseous ligand, that the intrinsic flexibility of the F-G loop appears essential to drive the heme sliding mechanism, and that residue Val 101 may act as a sensor of the interaction disruption between the heme and the distal histidine.
[hal-01688181] VLITL is a major cross-beta-sheet signal for fibrinogen A alpha-chain frameshift variants
Date: 24 avr 2018 - 15:01
Desc: The first case of hereditary fibrinogen A alpha-chain amyloidosis was recognized >20 years ago, but disease mechanisms still remain unknown. Here we report detailed clinical and proteomics studies of a French kindred with a novel amyloidogenic fibrinogen A alpha-chain frameshift variant, Phe521Leufs, causing a severe familial form of renal amyloidosis. Next, we focused our investigations to elucidate the molecular basis that render this A alpha-chain variant amyloidogenic. We show that a 49-mer peptide derived from the C-terminal part of the Phe521Leufs chain is deposited as fibrils in the patient's kidneys, establishing that only a small portion of Phe521Leufs directly contributes to amyloid formation in vivo. In silico analysis indicated that this 49-mer A alpha-chain peptide contained a motif (VLITL), with a high intrinsic propensity for beta-aggregation at residues 44 to 48 of human renal fibrils. To experimentally verify the amyloid propensity of VLITL, we generated synthetic Phe521Leufs-derived peptides and compared their capacity for fibril formation in vitro with that of their VLITL-deleted counterparts. We show that VLITL forms typical amyloid fibrils in vitro and is a major signal for cross-beta-sheet self-association of the 49-mer Phe521Leufs peptide identified in vivo, whereas its absence abrogates fibril formation. This study provides compelling evidence that VLITL confers amyloidogenic properties to A alpha-chain frameshift variants, yielding a previously unknown molecular basis for the pathogenesis of A alpha-chain amyloidosis.
[hal-02345034] Structural dataset from microsecond-long simulations of yeast mitofusin Fzo1 in the context of membrane docking
Date: 3 jan 2023 - 10:24
Desc: In this work we present a novel set of possible auto-oligomerisation states of yeast protein Fzo1 in the context of membrane docking. The dataset reports atomistic models and trajectories derived from a molecular dynamics study of the yeast mitofusin Fzo1, residues 101–855. The initial modelling was followed by coarse-grained molecular dynamics simulation to evaluate the stability and the dynamics of each structural model in a solvated membrane environment. Simulations were run for 1 μs and collected with GROMACS v5.0.4 using the martini v2.1 force field. For each structural model, the dataset comprises the production phase under semi-isotropic condition at 1 bar, 310 K and 150 mn NaCl. The integration step is 20 fs and coordinates have been saved every 1 ns. Each trajectory is associated with a ready-available visualization state for the VMD software. These structural detailed informations are a ready-available platform to plan integrative studies on the mitofusin Fzo1 and will aid the community to further elucidate the mitochondrial tethering process during membrane fusion. This dataset is based on the publication “Physics-based oligomeric models of the yeast mitofusin Fzo1 at the molecular scale in the context of membrane docking.” (Brandner and De Vecchis et al., 2019)”.
[hal-02289823] ATP Binding and Aspartate Protonation Enhance Photoinduced Electron Transfer in Plant Cryptochrome
Date: 17 sep 2019 - 11:40
Desc: Cryptochromes are flavoproteins encountered in most vegetal and animal species. They play a role of blue-light receptors in plants and in invertebrates. The putative resting state of the FAD cofactor in these proteins is its fully oxidized form, FADox. Upon blue-light excitation, the isoalloxazine ring (ISO) may undergo an ultrafast reduction by a nearby tryptophan residue W400. This primary reduction triggers a cascade of electron and proton transfers, ultimately leading to the formation of the FADH° radical. A recent experimental study has shown that the yield of FADH° formation in Arabidopsis cryptochrome can be strongly modulated by ATP binding and by pH, affecting the protonation state of D396 (proton donor to FAD°–). Here we provide a detailed molecular analysis of these effects by means of combined classical molecular dynamics simulations and time-dependent density functional theory calculations. When ATP is present and D396 protonated, FAD remains in close contact with W400, thereby enhancing electron transfer (ET) from W400 to ISO*. In contrast, deprotonation of D396 and absence of ATP introduce flexibility to the photoactive site prior to FAD excitation, with the consequence of increased ISO-W400 distance and diminished tunneling rate by almost two orders of magnitude. We show that under these conditions, ET from the adenine moiety of FAD becomes a competitive relaxation pathway. Overall, our data suggest that the observed effects of ATP and pH on the FAD photoreduction find their roots in the earliest stage of the photoreduction process; i.e., ATP binding and the protonation state of D396 determine the preferred pathway of ISO* relaxation.
Autres contacts
Institut de Biologie Physico-Chimique (IBPC)
13, rue Pierre et Marie Curie
75252 PARIS CEDEX 05