Noëlle Potier

Centre National de la Recherche Scientifique

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François H. Lallier

Station Biologique de Roscoff

C. Decker

Ifremer

Dino Moras

Institut de génétique et de biologie moléculaire et cellulaire

Emmanuelle Leize‐Wagner

Centre National de la Recherche Scientifique

Nathalie Zorn

Centre National de la Recherche Scientifique

Annick Dejaegere

Institut de génétique et de biologie moléculaire et cellulaire

Karine Olu

Ifremer

Alain Van Dorsselaer

Centre National de la Recherche Scientifique

Ann C. Andersen

Adaptation et Diversité en Milieu Marin

H. Lee Sweeney

University of Florida

Cooperative Institutions

Centre National de la Recherche Scientifique

Université de Strasbourg

Inserm

Institut de génétique et de biologie moléculaire et cellulaire

Integrated Structural Biology Grenoble

Université Paris Cité

Institut Curie

Sorbonne Université

Centre National pour la Recherche Scientifique et Technique (CNRST)

Institut de Biologie Moléculaire et Cellulaire

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Can the hemoglobin characteristics of vesicomyid clam species influence their distribution in deep-sea sulfide-rich sediments? A case study in the Angola Basin

Deep Sea Research Part II Topical Studies in Oceanography (2016)

C. Decker Nathalie Zorn J. Le Bruchec J.C. Caprais Noëlle Potier

10.1016/j.dsr2.2016.11.009

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Citations (23)

Structural identification of a bacterial quorum-sensing signal containing boron

Nature (2002)

Xin Chen Stephan Schauder Noëlle Potier Alain Van Dorsselaer István Pelczer

Autoinducer

10.1038/415545a

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Citations (1,498)

Globin’s Structure and Function in Vesicomyid Bivalves from the Gulf of Guinea Cold Seeps as an Adaptation to Life in Reduced Sediments

Physiological and Biochemical Zoology (2014)

C. Decker Nathalie Zorn Noëlle Potier Emmanuelle Leize‐Wagner François H. Lallier

Vesicomyid bivalves form dense clam beds in both deep-sea cold seeps and hydrothermal vents. The species diversity within this family raises questions about niche separation and specific adaptations. To compare their abilities to withstand hypoxia, we have studied the structure and function of erythrocyte hemoglobin (Hb) and foot myoglobin (Mb) from two vesicomyid species, Christineconcha regab and Laubiericoncha chuni, collected from the Regab pockmark in the Gulf of Guinea at a depth of 3,000 m. Laubiericoncha chuni possesses three monomeric globins, G1 (15,361 Da), G2 (15,668 Da), and G3 (15,682 Da) in circulating erythrocytes (Hb), and also three globins, G1, G3, and G4 (14,786 Da) in foot muscle (Mb). Therefore, globins G2 and G4 appear to be specific for erythrocytes and muscle, respectively, but globins G1 and G3 are common. In contrast, C. regab lacks erythrocyte Hb completely and possesses only globin monomers G1′ (14,941 Da), G2′ (15,169 Da), and G3′ (15,683 Da) in foot muscle. Thus, these two vesicomyid species, C. regab and L. chuni, show a remarkable diversity in globin expression when examined by electrospray ionization mass spectrometry. Oxygen-binding affinities reveal extremely high oxygen affinities (P50 < 1 Torr, from 5° to 15°C at pH 7.5), in particular L. chuni globins, which might be an advantage allowing L. chuni to dig deeply for sulfides and remain buried for long periods in reduced sediments.

Neuroglobin

10.1086/678131

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The “Phantom Effect” of the Rexinoid LG100754: Structural and Functional Insights

PLoS ONE (2010)

Yoshiteru Sato Nick Ramalanjaona Tiphaine Huet Noëlle Potier Judit Ősz

Retinoic acid receptors (RARs) and Retinoid X nuclear receptors (RXRs) are ligand-dependent transcriptional modulators that execute their biological action through the generation of functional heterodimers. RXR acts as an obligate dimer partner in many signalling pathways, gene regulation by rexinoids depending on the liganded state of the specific heterodimeric partner. To address the question of the effect of rexinoid antagonists on RAR/RXR function, we solved the crystal structure of the heterodimer formed by the ligand binding domain (LBD) of the RARα bound to its natural agonist ligand (all-trans retinoic acid, atRA) and RXRα bound to a rexinoid antagonist (LG100754). We observed that RARα exhibits the canonical agonist conformation and RXRα an antagonist one with the C-terminal H12 flipping out to the solvent. Examination of the protein-LG100754 interactions reveals that its propoxy group sterically prevents the H12 associating with the LBD, without affecting the dimerization or the active conformation of RAR. Although LG100754 has been reported to act as a ‘phantom ligand’ activating RAR in a cellular context, our structural data and biochemical assays demonstrate that LG100754 mediates its effect as a full RXR antagonist. Finally we show that the ‘phantom ligand effect’ of the LG100754 is due to a direct binding of the ligand to RAR that stabilizes coactivator interactions thus accounting for the observed transcriptional activation of RAR/RXR.

Retinoid X receptor

10.1371/journal.pone.0015119

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Citations (69)

The Asymmetric Binding of PGC-1α to the ERRα and ERRγ Nuclear Receptor Homodimers Involves a Similar Recognition Mechanism

PLoS ONE (2013)

Mária Takács Maxim V. Petoukhov Roger Atkinson Pierre Roblin François-Xavier Ogi

Background PGC-1α is a crucial regulator of cellular metabolism and energy homeostasis that functionally acts together with the estrogen-related receptors (ERRα and ERRγ) in the regulation of mitochondrial and metabolic gene networks. Dimerization of the ERRs is a pre-requisite for interactions with PGC-1α and other coactivators, eventually leading to transactivation. It was suggested recently (Devarakonda et al) that PGC-1α binds in a strikingly different manner to ERRγ ligand-binding domains (LBDs) compared to its mode of binding to ERRα and other nuclear receptors (NRs), where it interacts directly with the two ERRγ homodimer subunits. Methods/Principal Findings Here, we show that PGC-1α receptor interacting domain (RID) binds in an almost identical manner to ERRα and ERRγ homodimers. Microscale thermophoresis demonstrated that the interactions between PGC-1α RID and ERR LBDs involve a single receptor subunit through high-affinity, ERR-specific L3 and low-affinity L2 interactions. NMR studies further defined the limits of PGC-1α RID that interacts with ERRs. Consistent with these findings, the solution structures of PGC-1α/ERRα LBDs and PGC-1α/ERRγ LBDs complexes share an identical architecture with an asymmetric binding of PGC-1α to homodimeric ERR. Conclusions/Significance These studies provide the molecular determinants for the specificity of interactions between PGC-1α and the ERRs, whereby negative cooperativity prevails in the binding of the coactivators to these receptors. Our work indicates that allosteric regulation may be a general mechanism controlling the binding of the coactivators to homodimers.

Microscale Thermophoresis

Cooperative binding

Cooperativity

10.1371/journal.pone.0067810

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Citations (39)

The unique insert in myosin VI is a structural calcium–calmodulin binding site

Proceedings of the National Academy of Sciences (2004)

Amel Bahloul Guillaume Chevreux Amber L. Wells Davy Martin Jocelyn K. Nolt

Myosin VI contains an inserted sequence that is unique among myosin superfamily members and has been suggested to be a determinant of the reverse directionality and unusual motility of the motor. It is thought that each head of a two-headed myosin VI molecule binds one calmodulin (CaM) by means of a single “IQ motif”. Using truncations of the myosin VI protein and electrospray ionization(ESI)-MS, we demonstrate that in fact each myosin VI head binds two CaMs. One CaM binds to a conventional IQ motif either with or without calcium and likely plays a regulatory role when calcium binds to its N-terminal lobe. The second CaM binds to a unique insertion between the converter region and IQ motif. This unusual CaM-binding site normally binds CaM with four Ca 2+ and can bind only if the C-terminal lobe of CaM is occupied by calcium. Regions of the MD outside of the insert peptide contribute to the Ca 2+ –CaM binding, as truncations that eliminate elements of the MD alter CaM binding and allow calcium dissociation. We suggest that the Ca 2+ -CaM bound to the unique insert represents a structural CaM, and not a calcium sensor or regulatory component of the motor. This structure is likely an integral part of the myosin VI “converter” region and repositions the myosin VI “lever arm” to allow reverse direction (minus-end) motility on actin.

EF hand

10.1073/pnas.0306892101

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Citations (76)