Conformational change induced by binding of Mn ions activates SloR transcription factor in Streptococcus mutans.

Streptococcus mutans, a bacterium commonly found in the human oral cavity, is considered the primary causative agent of dental caries. A key player in the pathophysiology of S. mutans is SloR, a 25-kDa metalloregulatory protein.

Solvatomorphic Diversity in Coordination Compounds of Copper(II) with l-Homoserine and 1,10-Phenanthroline: Syntheses, Crystal Structures and ESR Study.

In this study, we report the syntheses, crystal structures and magnetic properties of ternary copper(II) coordination compounds with l-homoserine (l-Hhser) and 1,10-phenanthroline (phen). Six new coordination compounds were obtained: [Cu(l-hser)(HO)(phen)]SO·5HO (), [Cu(μ-l-hser)(HO)(phen)][Cu(l-hser)(HO)(phen)](SO)∙12HO (), {[Cu(μ-l-hser)(HO)(phen)][Cu(μ-l-hser)(phen)]SO·6HO} (), {[Cu(μ-l-hser)(HO)(phen)]SO·3HO} (), [Cu(l-hser)(HO)(phen)][Cu(l-hser)(CHOH)(phen)]SO·4HO () and {[Cu(l-hser)(CHOH)(phen)][Cu(μ-l-hser)(phen)]SO·5CHOH} () It was shown that slight differences in water content in the synthetic mixtures highly influence the final product, so in some cases, two or three different products were obtained. The compounds were characterized by single-crystal X-ray diffraction and ESR spectroscopy.

The Reversible Electron Transfer Within Stimuli-Responsive Hydrochromic Supramolecular Material Containing Pyridinium Oxime and Hexacyanoferrate (II) Ions.

The structural and electronic features of the stimuli-responsive supramolecular inter-ionic charge-transfer material containing electron accepting -benzylyridinium-4-oxime cation (BPA4) and electron donating hexacyanoferrate (II) are reported. The study of reversible stimuli-induced transformation between hydrated reddish-brown (BPA4)[Fe(CN)]·10HO and anhydrous blue (BPA4)[Fe(CN)] revealed the origin of observed hydrochromic behavior. The comparison of the crystal structures of decahydrate and anhydrous phase showed that subsequent exclusion/inclusion of lattice water molecules induces structural relocation of one BPA4 that alter the donor-to-acceptor charge-transfer states, resulting in chromotropism seen as reversible reddish-brown to blue color changes.

A homochiral tartrate-bridged dinuclear chromium(III) complex anion with a resonance-assisted hydrogen bond for proton conduction.

The synthesis of a homochiral building block based on L-tartrate-chromium(III) complex anions is reported. The dinuclear complex anion, which contains two bridging L-tartrate ligands and one aromatic N-donor ligand coordinated to chromium(III) ions, exhibits a boat conformation in which intramolecular resonance-assisted hydrogen bonding is present. The sodium L-tartrate-chromium(III) compound with the formula Na[Cr(bpy)(L-tart)H]·9HO (1) crystallizes from a methanol-water solution as a high water content material in the monoclinic space group 2.

Structural and dynamical changes of the Streptococcus gordonii metalloregulatory ScaR protein induced by Mn ion binding.

Divalent metal ions are essential micronutrients for many intercellular reactions. Maintaining their homeostasis is necessary for the survival of bacteria. In Streptococcus gordonii, one of the primary colonizers of the tooth surface, the cellular concentration of manganese ions (Mn) is regulated by the manganese-sensing transcriptional factor ScaR which controls the expression of proteins involved in manganese homeostasis.