2Dengue disease is caused by four different flavivirus 1 serotypes, which infect 390 million people yearly with 25% symptomatic cases 2 and for which no licensed vaccine is available. Recent phase III vaccine trials showed partial protection, and in particular no protection for dengue virus serotype 2 (DENV--2) 3,4 . Structural studies so far have characterized only epitopes recognized by serotype specific human antibodies 5,6 . We recently isolated human antibodies potently neutralizing all four DENV serotypes 7 . Here we describe the X--ray structures of four of these broadly neutralizing antibodies (bnAbs) in complex with the envelope glycoprotein E from DENV--2, revealing that the recognition determinants are at a serotype conserved site at the E dimer interface, including the exposed main chain of the E fusion loop 8 and the two conserved glycan chains.This "E--dimer dependent epitope" (EDE) is also the binding site for the viral glycoprotein prM during virus maturation in the secretory pathway of the infected cell 9 , explaining its conservation across serotypes and highlighting an Achilles heel of the virus with respect to antibody neutralization. These findings will be instrumental for devising novel immunogens to protect simultaneously against all four serotypes of dengue virus.Exposed at the surface of infectious mature DENV particles, protein E is the sole target of neutralizing antibodies. It displays an icosahedral arrangement in which 90 E dimers completely coat the viral surface 10,11 and which is sensitive to the environmental pH. Upon entry of DENV into cells via receptor--mediated endocytosis, the acidic 3 endosomal environment triggers an irreversible fusogenic conformational change in E that leads to fusion of viral and endosomal membranes 1 . The structure of the isolated E dimer has been determined by X--ray crystallography using the soluble ectodomain (sE) 8,12 . Protein E is relatively conserved, displaying about 65% amino acid sequence identity when comparing the most distant DENV serotypes. In particular, there are two conserved N--linked glycosylation sites at positions N67 and N153. To examine its interaction with the antibodies, we selected four highly potent bnAbs identified in the accompanying work: 747(4) A11 and 747 B7 (EDE2 group, requiring glycosylation at position N153 for efficient binding) and 752--2 C8 and 753(3) C10 (EDE1 group, binding regardless of the glycosylation at N153) 7 -referred to as A11, B7, C8 and C10 from hereon. The EDE2 bnAbs were isolated from the same patient (who had a secondary infection with DENV--2), and are somatic variants of the same IgG clone, derived from the IGHV3--74 and IGLV2--23 germ lines. The heavy chain has a very long (26 amino acids, IMGT convention) complementarity--determining region 3 (CDR H3). The EDE1 bnAbs were isolated from different patients and derive from (EDE1 C8, the patient appeared to have a primary infection of undetermined serotype) and IGHV1--3* and IGLV2--14 (EDE1 C10, from a patient with secondary DENV--1 infecti...

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Proton conductive materials are of significant importance and highly desired for clean energy-related applications. Discovery of practical metal-organic frameworks (MOFs) with high proton conduction remains a challenge due to the use of toxic chemicals, inconvenient ligand preparation and complication of production at scale for the state-of-the-art candidates. Herein, we report a zirconium-MOF, MIP-202(Zr), constructed from natural α-amino acid showing a high and steady proton conductivity of 0.011 S cm−1 at 363 K and under 95% relative humidity. This MOF features a cost-effective, green and scalable preparation with a very high space-time yield above 7000 kg m−3 day−1. It exhibits a good chemical stability under various conditions, including solutions of wide pH range and boiling water. Finally, a comprehensive molecular simulation was carried out to shed light on the proton conduction mechanism. All together these features make MIP-202(Zr) one of the most promising candidates to approach the commercial benchmark Nafion.

Glycogen and starch are the major readily accessible energy storage compounds in nearly all living organisms. Glycogen is a very large branched glucose homopolymer containing about 90% a-1,4-glucosidic linkages and 10% a-1,6 linkages. Its synthesis and degradation constitute central pathways in the metabolism of living cells regulating a global carbon/energy buffer compartment. Glycogen biosynthesis involves the action of several enzymes among which glycogen synthase catalyzes the synthesis of the a-1,4-glucose backbone. We now report the first crystal structure of glycogen synthase in the presence and absence of adenosine diphosphate. The overall fold and the active site architecture of the protein are remarkably similar to those of glycogen phosphorylase, indicating a common catalytic mechanism and comparable substratebinding properties. In contrast to glycogen phosphorylase, glycogen synthase has a much wider catalytic cleft, which is predicted to undergo an important interdomain 'closure' movement during the catalytic cycle. The structures also provide useful hints to shed light on the allosteric regulation mechanisms of yeast/mammalian glycogen synthases.

cis-diamminedichloroplatinum (II) (cisplatin) is a powerful anti-tumor drug whose target is cellular DNA. In the reaction between DNA and cisplatin, covalent intrastrand and interstrand cross-links (ICL) are formed. Two solution structures of the ICL have been published recently. In both models the double-helix is bent and unwound but with significantly different angle values. We solved the crystal structure at 100K of a double-stranded DNA decamer containing a single cisplatin ICL, using the anomalous scattering (MAD) of platinum as a unique source of phase information. We found 47 degrees for double-helix bending and 70 degrees for unwinding in agreement with previous electrophoretic assays. The crystals are stabilized by intermolecular contacts involving two cytosines extruded from the double-helix, one of which makes a triplet with a terminal G.C pair. The platinum coordination is nearly square and the platinum residue is embedded into a cage of nine water molecules linked to the cross-linked guanines, to the two amine groups, and to the phosphodiester backbone through other water molecules. This water molecule organization is discussed in relation with the chemical stability of the ICL.