Multi-Component Crystals of 2,2′-Bipyridine with Aliphatic Dicarboxylic Acids: Melting Point-Structure Relations

The aim of the study was to investigate the relationship between the melting point and the supramolecular structure of three multi-component crystals of aliphatic dicarboxylic acids with 2,2′-bipyridine and to investigate the conformations of 2,2′-bipyridine in published multi-component crystals. The crystals were prepared using the solvent evaporation method and were characterized using single-crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), and differential scanning calorimetry (DSC). The crystal structures were further analyzed using CrystalExplorer, and the results were correlated with the melting points. The results of the conformation analysis of the reported multi-component crystals of 2,2′-bipyridine are also presented.

New Insights into the Reactivity of 2-Halo-Glycals. Synthesis of Novel Iodinated Oand S-Glycosides

<p><i>This is the first report on the Ferrier rearrangement of 2-halo-glycals with S-nucleophiles. We present herein the selective synthesis of new 2-iodo-2,3-unsaturated O- and S-glycosides. We obtained in good yields and high anomeric selectivity </i><i>a</i><i>-glycosydes. As a particular behaviour, we also describe heteroaromatic thio sugar derivatives were the C3 addition was performed in an alternative mechanism. A complete structure and conformation analysis by NMR was also presented. </i></p>

New Insights into the Reactivity of 2-Halo-Glycals. Synthesis of Novel Iodinated Oand S-Glycosides

<p><i>This is the first report on the Ferrier rearrangement of 2-halo-glycals with S-nucleophiles. We present herein the selective synthesis of new 2-iodo-2,3-unsaturated O- and S-glycosides. We obtained in good yields and high anomeric selectivity </i><i>a</i><i>-glycosydes. As a particular behaviour, we also describe heteroaromatic thio sugar derivatives were the C3 addition was performed in an alternative mechanism. A complete structure and conformation analysis by NMR was also presented. </i></p>

Conjugated activation of myocardial-specific transcription of Gja5 by a pair of Nkx2-5-Shox2 co-responsive elements

The sinoatrial node (SAN) is the primary pacemaker in the heart. During cardiogenesis, Shox2 and Nkx2-5 are co-expressed in the junction domain of the SAN and regulate pacemaker cell fate through a Shox2-Nkx2-5 antagonism. Cx40 is a marker of working myocardium and an Nkx2-5 transcriptional output antagonized by Shox2, but the underlying regulatory mechanisms remain elusive. Here we characterized a bona fide myocardial-specific Gja5 (coding gene of Cx40) distal enhancer consisting of a pair of Nkx2-5 and Shox2 co-bound elements in the regulatory region of Gja5. Transgenic reporter assays revealed that neither element alone, but the conjugation of both elements together, drives myocardial-specific transcription. Genetic analyses confirmed that the activation of this enhancer depends on Nkx2-5 but is inhibited by Shox2 in vivo, and its presence is essential for Gja5 expression in the myocardium but not the endothelial cells of the heart. Furthermore, chromatin conformation analysis showed an Nkx2-5-dependent loop formation between these two elements and the Gja5 promoter in vivo, indicating that Nkx2-5 bridges the conjugated activation of this enhancer by pairing the two elements to the Gja5 promoter.

A disulfide constrains the ToxR periplasmic domain structure, altering its interactions with ToxS and bile-salts

ToxR is a transmembrane transcription factor that, together with its integral membrane periplasmic binding partner ToxS, is conserved across the Vibrio family. In some pathogenic Vibrios, including V. parahaemolyticus and V. cholerae, ToxR is required for bile resistance and virulence, and ToxR is fully activated and protected from degradation by ToxS. ToxS achieves this in part by ensuring formation of an intra-chain disulfide bond in the C-terminal periplasmic domain of ToxR (dbToxRp). In this study, biochemical analysis showed dbToxRp to have a higher affinity for the ToxS periplasmic domain than the non-disulfide bonded conformation. Analysis of our dbToxRp crystal structure showed this is due to disulfide bond stabilization. Furthermore, dbToxRp is structurally homologous to the V. parahaemolyticus VtrA periplasmic domain. These results highlight the critical structural role of disulfide bond in ToxR and along with VtrA define a domain fold involved in environmental sensing conserved across the Vibrio family.