Induced Fit of C2 H2 in a Flexible MOF Through Cooperative Action of Open Metal Sites.

Porous materials that can undergo pore-structure adjustment to better accommodate specific molecules are ideal for separation and purification. Here, we report a stable microporous metal-organic framework, JNU-1, featuring one-dimensional diamond-shaped channels with a high density of open metal sites arranged on the surface for the cooperative binding of acetylene. Together with its framework flexibility and appropriate pore geometry, JNU-1 exhibits an induced-fit behavior for acetylene. The specific binding sites and continuous framework adaptation upon increased acetylene pressure are validated by molecular modeling and in situ X-ray diffraction study. This unique induced-fit behavior endows JNU-1 with an unprecedented increase in the acetylene binding affinity (adsorption enthalpy: up to 47.6 kJ mol-1 at ca. 2.0 mmol g-1 loading).

The AdcR-regulated AdcA and AdcAII contribute additively to zinc acquisition and virulence in Streptococcus suis.

Metals are necessary elements for bacteria. Typically, vertebrate hosts restrict invading bacterial pathogens from accessing metals. Therefore, bacteria have evolved high-affinity metal importers to acquire metals. Streptococcus suis is a major swine pathogen and an emerging zoonotic agent that endangers the swine industry and human health worldwide. Herein, we aimed to identify the zinc acquisition systems in S. suis and evaluate their roles in bacterial virulence. Bioinformatic analyses revealed that S. suis encodes homologues of AdcA and AdcAII, two well-characterised Zn-binding lipoproteins in certain streptococci. Quantitative reverse transcription PCR (qRT-PCR) analysis revealed that the expressions of adcA and adcAII were significantly upregulated in response to Zn limitation, with a higher expression level of adcAII than adcA. Gene deletion mutants and complementation strains were constructed; their growth characteristics under Zn-deficient and Zn-replete conditions indicated that AdcA and AdcAII have overlapping functionality in Zn acquisition. A mouse infection model was used to evaluate the roles of AdcA and AdcAII in S. suis virulence. Mice infected with the double mutant ΔadcAΔadcAII exhibited a significantly higher survival rate, decreased bacterial burden, and lower production of inflammatory cytokines compared to those infected with the wild type (WT) strain. Furthermore, ΔadcAΔadcAII showed reduced competitiveness in infection establishment compared with the WT strain. RNA sequencing, qRT-PCR, and electrophoretic mobility shift assays revealed that AdcR negatively regulates the expressions of adcA and adcAII. Collectively, our results demonstrated that AdcA and AdcAII, which are negatively regulated by AdcR, contribute additively to zinc acquisition and virulence in S. suis.

A chemopalette strategy for white light by modulating monomeric and excimeric phosphorescence of a simple Cu(i) cyclic trinuclear unit.

Room-temperature white phosphorescence with a quantum yield (QY) of 35.6% and a CIE coordinate of (0.33, 0.37) is observed for Cl-α, the crystal of cyclic Cu3(4-chloropyrazolate)3. Its white light consists of comparably uncommon monomeric blue and common excimeric yellow phosphorescence associated with Cu3(pyrazolate)3, achieved by multiple non-covalent interactions involving chlorine.