Structural and functional characterization of an egg-laying hormone signaling system in a lophotrochozoan - The pacific oyster (Crassostrea gigas).

The egg-laying hormones (ELHs) of gastropod mollusks were characterized more than forty years ago. Yet, they have remained little explored in other mollusks. To gain insights into the functionality of the ELH signaling system in a bivalve mollusk - the oyster Crassostrea gigas, this study investigates the processing of its ELH precursor (Cragi-ELH) by mass spectrometry.

Mechanism of action of -encoded type I toxins in : from membrane alterations to mesosome-like structures formation and bacterial lysis.

SprF1 is a type I toxin-antitoxin system located on prophage. It has previously been shown that the two toxins, SprG1 and SprG1, encoded by the gene, are two membrane-associated peptides structured in a single α-helix. Overexpression of these two peptides leads to growth inhibition and even death.

Structural and Functional Characterization of Orcokinin B-like Neuropeptides in the Cuttlefish ().

The cuttlefish () is a Cephalopod mollusk that lives in the English Channel and breeds in coastal spawning grounds in spring. A previous work showed that the control of egg-laying is monitored by different types of regulators, among which neuropeptides play a major role. They are involved in the integration of environmental cues, and participate in the transport of oocytes in the genital tract and in the secretion of capsular products.

NMR structural elucidation of dehydrodimers resulting from oxidation of 5-O-caffeoylquinic acid in an apple juice model solution.

During apple juice and cider-making processes, phenolic compounds undergo enzymatic oxidation. 5-O-caffeoylquinic acid (CQA) is one of the major hydroxycinnamic acid derivatives and it is the preferential substrate for polyphenol oxidase (PPO) in apple juices. Consequently, CQA dehydrodimers (MW 706 Da) are among the main products resulting from CQA oxidation.

Alterins Produced by Oyster-Associated Are Antibacterial Cyclolipopeptides with LPS-Binding Activity.

Discovery after discovery, host-associated microbiota reveal a growing list of positive effects on host homeostasis by contributing to host nutrition, improving hosts' immune systems and protecting hosts against pathogens. In that context, a collection of oyster associated bacteria producing antibacterial compounds have been established to evaluate their role in non-host-derived immunity. Here, we described alterins; potent anti-Gram negative compounds produced by h-6 and h-42 isolated from different healthy oyster hemolymph.

Novel antibiotics effective against gram-positive and -negative multi-resistant bacteria with limited resistance.

Antibiotics are a medical wonder, but an increasing frequency of resistance among most human pathogens is rendering them ineffective. If this trend continues, the consequences for public health and for the general community could be catastrophic. The current clinical pipeline, however, is very limited and is dominated by derivatives of established classes, the "me too" compounds.

Impact of polyphenols on receptor-ligand interactions by NMR: the case of neurotensin (NT)-neurotensin receptor fragment (NTS1) complex.

Ligand-receptor interactions can be implicated in many pathological events such as chronic neurodegenerative diseases. Thus, the discovery of molecules disrupting this type of interactions could be an interesting therapeutic approach. Polyphenols are well known for their affinity for proteins and several studies have characterized these direct interactions.

B1.12: a novel peptide interacting with the extracellular loop of the EBV oncoprotein LMP1.

Latent membrane protein 1 (LMP1) encoded by the Epstein-Barr virus (EBV) plays an important role in EBV-induced cell transformation. Down-regulation of the LMP1 expression had shown promising results on cancer cell therapy. In this study, we identified by Phage display a novel peptide called B1.

Novel Antifungal Compounds, Spermine-Like and Short Cyclic Polylactates, Produced by in Yogurt.

was described as endowed with high antifungal activity. Most of the studies associated this activity to the produced organic acids, i.e.

Human Dystrophin Structural Changes upon Binding to Anionic Membrane Lipids.

Scaffolding proteins play important roles in supporting the plasma membrane (sarcolemma) of muscle cells. Among them, dystrophin strengthens the sarcolemma through protein-lipid interactions, and its absence due to gene mutations leads to the severe Duchenne muscular dystrophy. Most of the dystrophin protein consists of a central domain made of 24 spectrin-like coiled-coil repeats (R).

Dystrophin's central domain forms a complex filament that becomes disorganized by in-frame deletions.

Dystrophin, encoded by the gene, is critical for maintaining plasma membrane integrity during muscle contraction events. Mutations in the gene disrupting the reading frame prevent dystrophin production and result in severe Duchenne muscular dystrophy (DMD); in-frame internal deletions allow production of partly functional internally deleted dystrophin and result in less severe Becker muscular dystrophy (BMD). Many known BMD deletions occur in dystrophin's central domain, generally considered to be a monotonous rod-shaped domain based on the knowledge of spectrin family proteins.

Selectivity Modulation and Structure of α/aza-β Cyclic Antimicrobial Peptides.

Potent and selective antimicrobial cyclic pseudopeptides (ACPPs) mixing α- and aza-β -amino acids were developed. Cyclopseudopeptide sequences were designed to investigate the impact of some intrinsic molecular parameters on their biological activities. Fine changes in the nature of the side chains strongly modulated the selectivity of the ACPPs with regard to hemolysis versus antimicrobial activity.

Crustacean cardioactive peptides: Expression, localization, structure, and a possible involvement in regulation of egg-laying in the cuttlefish Sepia officinalis.

The cuttlefish (Sepia officinalis) is a cephalopod mollusk distributed on the western European coast, in the West African Ocean and in the Mediterranean Sea. On the Normandy coast (France), cuttlefish is a target species of professional fishermen, so its reproduction strategy is of particular interest in the context of stock management. Egg-laying, which is coastal, is controlled by several types of regulators among which neuropeptides.

Contrast-Matched Isotropic Bicelles: A Versatile Tool to Specifically Probe the Solution Structure of Peripheral Membrane Proteins Using SANS.

Obtaining structural information on integral or peripheral membrane proteins is currently arduous due to the difficulty of their solubilization, purification, and crystallization (for X-ray crystallography (XRC) application). To overcome this challenge, bicelles are known to be a versatile tool for high-resolution structure determination, especially when using solution and/or solid state nuclear magnetic resonance (NMR) and, to a lesser extent, XRC. For proteins not compatible with these high-resolution methods, small-angle X-ray and neutron scattering (SAXS and SANS, respectively) are powerful alternatives to obtain structural information directly in solution.

Bioactive Metabolites from the Deep Subseafloor Fungus Oidiodendron griseum UBOCC-A-114129.

Four bioactive compounds have been isolated from the fungus UBOCC-A-114129 cultivated from deep subsurface sediment. They were structurally characterized using a combination of LC-MS/MS and NMR analyses as fuscin and its derivatives (dihydrofuscin, dihydrosecofuscin, and secofuscin) and identified as polyketides. Albeit those compounds were already obtained from terrestrial fungi, this is the first report of their production by an species and by the deepest subseafloor isolate ever studied for biological activities.

Minor Pyranonaphthoquinones from the Apothecia of the Lichen Ophioparma ventosa.

Four new quinonoid naphthopyranones, ophioparmin (1), 4-methoxyhaemoventosins (2a and 2b), and 4-hydroxyhaemoventosin (3), together with anhydrofusarubin lactone (4) and haemoventosin (5) were isolated from the fruiting bodies of Ophioparma ventosa, a crustose lichen. Their structures were determined by spectroscopic analyses, and the absolute configurations of 1 and 2 were elucidated through experimental and calculated electronic circular dichroism analyses. Compounds 1, 2, and 5 exhibited moderate to strong antioxidant activities.

Two distinct conformational states of Mycobacterium tuberculosis virulent factor early secreted antigenic target 6 kDa are behind the discrepancy around its biological functions.

Early secreted antigenic target 6 kDa (ESAT-6) and culture filtrate protein 10 kDa (CFP-10) are complex proteins secreted by Mycobacterium tuberculosis that play a major role in the pathogenesis of tuberculosis. However, studies focusing on the biological functions of ESAT-6 led to discordant results and the role of ESAT-6 remains controversial. In the present study, we aim to address a potential explanation for this discrepancy and to highlight the physiological impact of two conformational states of ESAT-6.

Heterobi- and -trimetallic Ion Pairs of Zirconocene-Based Isoselective Olefin Polymerization Catalysts with AlMe₃.

The reactivity towards AlMe3 of discrete cationic ansa-zirconocenes 2 a,b that are ubiquitously used in isoselective propylene polymerization and based on [{Ph(H)C(3,6-tBu2-Flu)(3-tBu-5-Et-Cp)}ZrMe2)] {Cp-Flu} and rac-[{Me2Si-(2-Me-4-Ph-Ind)2}ZrMe2] {SBI} was scrutinized. The first example of a structurally characterized Group 4 metallocene AlMe3 adduct (3 b) is reported. In the presence of excess AlMe3, the {SBI}-based AlMe3 adduct 3 b undergoes a slow decomposition via C-H activation in a bridging methyl unit to yield a new species (4 b) with a trimetallic {Zr(μ-CH2)(μ-Me)AlMe(μ-Me)AlMe2} core.

Easy and quantitative access to Fe(II) and Fe(III) di(aryl)alkynylphosphine oxides featuring [Fe(dppe)Cp*] endgroups: terminal P=O functionality blocks the dimerisation of the Fe(III) derivatives.

A series of paramagnetic di(aryl)alkynylphosphine oxides [PF6] featuring an open-shell [Fe(κ(2)-dppe)(η(5)-C5Me5)](+) endgroup were obtained by oxidation of their neutral Fe(II) parents 3a-c, themselves obtained in a simple and nearly quantitative fashion from the corresponding Fe(II) metallophosphines 1a-c. The new organometallic radicals were characterised by NMR and ESR and were shown to be perfectly stable in solution, in contrast to species such as 1a-b[PF6] which readily dimerise.

Peptidic ligands to control the three-dimensional self-assembly of quantum rods in aqueous media.

The use of peptidic ligands is validated as a generic chemical platform allowing one to finely control the organization in solid phase of semiconductor nanorods originally dispersed in an aqueous media. An original method to generate, on a macroscopic scale and with the desired geometry, three-dimensional supracrystals composed of quantum rods is introduced. In a first step, nanorods are transferred in an aqueous phase thanks to the substitution of the original capping layer by peptidic ligands.

Sterols associated with small unilamellar vesicles (SUVs): intrinsic mobility role for 1H NMR detection.

Small unilamellar vesicles (SUVs) of phospholipids are often used as a membrane model system for studying the interaction of molecules. When using NMR under the standard liquid-state conditions, SUV phospholipid proton spectra can be recorded, exhibiting sharp signals. This is not only because of the fast vesicular tumbling but also because of the combination of this tumbling with the individual motion of the lipids inside the bilayer.

Triarylphosphine ligands with pendant electron-rich "[Fe(κ2-dppe)(η5-C5Me5)(C≡C)]-" substituents.

The synthesis of four triaylphosphine ligands featuring electron-rich Fe(II) "Fe(κ(2)-dppe)(η(5)-C5Me5)C≡C-" pendant substituents in para and meta position(s) (1-4) is reported along with that of their corresponding radical cations (1-2[PF6] or 3-4[PF6]3). These triarylphosphines possessing redox-active organometallic substituents constitute a new class of phosphorus-based metallo-ligands. In contrast to many related ferrocenylphosphines, these metallo-ligands are stable and isolable in two redox-states.

Synthesis of stachybotrin C and all of its stereoisomers: structure revision.

We disclose the first total synthesis of stachybotrin C, a potent neuroprotective natural compound. All of the four stereoisomers have been prepared and fully characterized with the aim to attribute the absolute configuration of the two adjacent stereocenters of the stachybotrin C.

Unprecedented 17-residue peptaibiotics produced by marine-derived Trichoderma atroviride.

In the course of investigations on marine-derived toxigenic fungi, five strains of Trichoderma atroviride were studied for their production of peptaibiotics. While these five strains were found to produce classical 19-residue peptaibols, three of them exhibited unusual peptidic sodium-adduct [M + 2 Na](2+) ion peaks at m/z between 824 and 854. The sequencing of these peptides led to two series of unprecedented 17-residue peptaibiotics based on the model Ac-XXX-Ala-Ala-XXX-XXX-Gln-Aib-Aib-Aib-Ala/Ser-Lxx-Aib-Pro-XXX-Aib-Lxx-[C(129) ].

Ligerin, an antiproliferative chlorinated sesquiterpenoid from a marine-derived Penicillium strain.

A new chlorinated sesquiterpenoid analogue of fumagillin, ligerin (1), was isolated from a marine-derived strain of Penicillium, belonging to the subgenus Penicillium, along with the known compounds penicillic acid (2), orcinol, and orsellinic acid. Chemical structures were established by an interpretation of spectroscopic data including IR, UV, and HRESIMS, together with analyses of 1D and 2D NMR spectra and X-ray analysis for the determination of the absolute configuration. Ligerin (1) displayed strong inhibitory activity against an osteosarcoma cell line.