Allosteric regulation by c-di-AMP modulates a complete N-acetylglucosamine signaling cascade in Saccharopolyspora erythraea.

c-di-AMP is an essential and widespread nucleotide second messenger in bacterial signaling. For most c-di-AMP synthesizing organisms, c-di-AMP homeostasis and the molecular mechanisms pertaining to its signal transduction are of great concern. Here we show that c-di-AMP binds the N-acetylglucosamine (GlcNAc)-sensing regulator DasR, indicating a direct link between c-di-AMP and GlcNAc signaling. Beyond its foundational role in cell-surface structure, GlcNAc is attractive as a major nutrient and messenger molecule regulating multiple cellular processes from bacteria to humans. We show that increased c-di-AMP levels allosterically activate DasR as a master repressor of GlcNAc utilization, causing the shutdown of the DasR-mediated GlcNAc signaling cascade and leading to a consistent enhancement in the developmental transition and antibiotic production in Saccharopolyspora erythraea. The expression of disA, encoding diadenylate cyclase, is directly repressed by the regulator DasR in response to GlcNAc signaling, thus forming a self-sustaining transcriptional feedback loop for c-di-AMP synthesis. These findings shed light on the allosteric regulation by c-di-AMP, which appears to play a prominent role in global signal integration and c-di-AMP homeostasis in bacteria and is likely widespread in streptomycetes that produce c-di-AMP.

Protein acylation links metabolism and the control of signal transduction, transcription regulation, growth, and pathogenicity in Actinobacteria.

Actinobacteria have a complex life cycle, including morphological and physiological differentiation which are often associated with the biosynthesis of secondary metabolites. Recently, increased interest in post-translational modifications (PTMs) in these Gram-positive bacteria has highlighted the importance of PTMs as signals that provide functional diversity and regulation by modifying proteins to respond to diverse stimuli. Here, we review the developments in research on acylation, a typical PTM that uses acyl-CoA or related metabolites as donors, as well as the understanding of the direct link provided by acylation between cell metabolism and signal transduction, transcriptional regulation, cell growth, and pathogenicity in Actinobacteria.

Fullerene-Derived Carbon Nanotubes and Their Electrocatalytic Properties in Oxygen Reduction and Zn-Air Batteries.

Carbon-based materials with superior electrochemical performances have been prepared from fullerenes by releasing their intrinsic advantages such as pentagon defects and π-electron carbons. To the best of our knowledge, fullerene-derived carbon nanotubes (CNTs) and their electrochemical behavior have not been experimentally investigated. In this work, in situ growth of CNT composites from fullerene is realized via a self-catalyzed process by employing an Fe-decorated fullerene (ferrocenylpyrrolidine C60) as the precursor and NH3 as the pyrolysis atmosphere. The results show that the in situ Fe doping in fullerene, the self-assembly of fullerene molecules, the pyrolysis temperature, and the NH3 flow play essential roles in the generation of CNTs. The as-prepared MN7-10/3 CNT composite exhibits efficient oxygen reduction performance with E1/2 = 0.82 V and Eon = 1.02 V vs the RHE. The flexible solid-state Zn-air battery constructed based on MN7-10/3 exhibits a superior power density (109.3 mW cm-2 at 180.9 mA cm-2) and long-term durability (the voltage remains at 95.6% of the initial value after discharging for 5000 s) compared with the benchmark Pt/C catalyst. The transformation of the Fe-decorated fullerene to CNTs reveals a new function of fullerenes and demonstrates a new solid-state synthetic method for CNTs.

From 3D hierarchical microspheres to 1D microneedles: the unique role of water in the morphology control of ferrocenylpyrrolidine C60 microcrystals.

Fullerene microcrystals have been well prepared by the conventional liquid-liquid interface precipitation (LLIP) method, and the crystal structures can be manipulated by solvent combination. Aromatic and alcoholic solvents are widely used as good and poor solvents, respectively, in LLIP. However, water with higher polarity has been rarely utilized as a poor solvent for the morphology engineering of fullerenes, particularly in the morphology control of fullerene derivatives. Herein, the water-regulated morphology of a fullerene derivative, namely ferrocenylpyrrolidine C60 (denoted as FC), is investigated via the LLIP method. By simply modulating the combination of a good solvent (aromatic isopropylbenzene, IPB) and the poor solvents (alcohols), three-dimensional (3D) hierarchical microspheres of FC are obtained. Surprisingly, when water is introduced as one of poor solvents in the LLIP process, one-dimensional (1D) microneedles are obtained. The presence of water controls the liquid-liquid interface, the external environment and kinetics of the crystal growth, thereby promoting the morphological evolution from 3D hierarchical microspheres to 1D microneedles. Moreover, the solvated 1D microneedles exhibit enhanced photoluminescence (PL) and photocurrent responses in virtue of the highly ordered molecule arrangement and solvent (IPB) embedding in the crystal lattice. The water-regulated morphology engineering of FC provides a new strategy for the growth and morphology control of fullerene microcrystals.

Eco-friendly synthesis of N,S co-doped hierarchical nanocarbon as a highly efficient metal-free catalyst for the reduction of nitroarenes.

Heteroatom-doped carbon nanomaterials are effective metal-free catalysts for organic reactions. However, S-doped carbocatalysts are relatively unexplored due to challenges related to the synthesis of S-doped nanocarbon. Herein, we employed a facile, low-cost and eco-friendly approach to construct a N,S co-doped hierarchical carbon nanomaterial (NSHC) via the pyrolysis of an azo-sulphonate dye pollutant intercalated layered double hydroxide. The as-prepared NSHC possesses a two-dimensional hierarchical porous structure with ultrathin carbon nanosheets uniformly distributed on hexagonal carbon nanoplates, endowing the material with a high specific surface area of 1260 m2 g-1. Attributed to the synergistic effects of N,S co-doping, the high specific surface area and the interconnected porous architecture, NSHC demonstrates excellent catalytic activity and selectivity in the reduction of nitroarenes. Among the reported carbocatalysts for nitrobenzene reduction using hydrazine hydrate, NSHC shows the highest turnover frequency value of 4.89 h-1. Furthermore, NSHC exhibits remarkable recyclability and generality for the reduction of various aromatic nitro compounds.

A facile strategy to synthesize three-dimensional Pd@Pt core-shell nanoflowers supported on graphene nanosheets as enhanced nanoelectrocatalysts for methanol oxidation.

Here we demonstrate for the first time a water-based surfactant-free synthesis of three-dimensional porous Pd@Pt core-shell nanoflowers on graphene. The obtained Pd@Pt-graphene hybrids exhibited substantially enhanced electrocatalytic activity and stability relative to the commercial Pt/C catalyst originating from this exquisite nanoarchitecture for three-dimensional molecular accessibility and graphene-metal interaction.