The root microbiota is critical for agricultural yield, with growth-promoting bacteria able to solubilise phosphate, produce plant growth hormones, antagonise pathogens and fix N
2
. Plants control the microorganisms in their immediate environment and this is at least in part through direct selection, the immune system, and interactions with other microorganisms. Considering the importance of the root microbiota for crop yields it is attractive to artificially regulate this environment to optimise agricultural productivity. Towards this aim we express a synthetic pathway for the production of the rhizopine
scyllo
-inosamine in plants. We demonstrate the production of this bacterial derived signal in both
Medicago truncatula
and barley and show its perception by rhizosphere bacteria, containing bioluminescent and fluorescent biosensors. This study lays the groundwork for synthetic signalling networks between plants and bacteria, allowing the targeted regulation of bacterial gene expression in the rhizosphere for delivery of useful functions to plants.
The cycloisomerization of allene-enol ethers under Bi(OTf)3 catalysis was developed as a novel "atom-economic" tool for accessing interesting functionalized cyclopentene rings. Bi(OTf)3 was shown to promote selectively the activation of the enol ether moiety of the substrate. This catalytic methodology was further extended to the synthesis of dihydrofuran and oxaspirocycle derivatives.
Glycosaminoglycan (GAG)-protein interactions mediate critical physiological and pathological processes, such as neuronal plasticity, development, and viral invasion. However, mapping GAG-protein interaction networks is challenging as these interactions often require specific GAG sulfation patterns and involve transmembrane receptors or extracellular matrix-associated proteins. Here, we report the first GAG polysaccharidebased photoaffinity probes for the system-wide identification of GAG-binding proteins in living cells. A general platform for the modular, efficient assembly of various chondroitin sulfate (CS)-based photoaffinity probes was developed. Systematic evaluations led to benzophenonecontaining probes that efficiently and selectively captured known CS-E-binding proteins in vitro and in cells. Importantly, the probes also enabled the identification of >50 new proteins from living neurons that interact with the neuroplasticity-relevant CS-E sulfation motif. Several candidates were independently validated and included membrane receptors important for axon guidance, innate immunity, synapse development, and synaptic plasticity. Overall, our studies provide a powerful approach for mapping GAG-protein interaction networks, revealing new potential functions for these polysaccharides and linking them to diseases such as Alzheimer's and autism.
We report the synthesis of deuterium-labelled derivatives of phosphatidylinositol 4-phosphate and phosphatidylinositol 5-phosphate, and demonstrate their use in quantifying levels of endogenous phospholipids in cells.
A series of readily available allenic aldehydes and their alcohol, acetate and enol ether derivatives have been prepared and evaluated for their olfactory properties. The tested compounds revealed interesting fruity, floral and woody aspects as the main notes.
Glycan alterations are associated with aging, neuropsychiatric, and neurodegenerative diseases, although the contributions of specific glycan structures to emotion and cognitive functions remain largely unknown. Here, we used a combination of chemistry and neurobiology to show that 4-
O
-sulfated chondroitin sulfate (CS) polysaccharides are critical regulators of perineuronal nets (PNNs) and synapse development in the mouse hippocampus, thereby affecting anxiety and cognitive abilities such as social memory. Brain-specific deletion of CS 4-
O
-sulfation in mice increased PNN densities in the area CA2 (cornu ammonis 2), leading to imbalanced excitatory-to-inhibitory synaptic ratios, reduced CREB activation, elevated anxiety, and social memory dysfunction. The impairments in PNN densities, CREB activity, and social memory were recapitulated by selective ablation of CS 4-
O
-sulfation in the CA2 region during adulthood. Notably, enzymatic pruning of the excess PNNs reduced anxiety levels and restored social memory, while chemical manipulation of CS 4-
O
-sulfation levels reversibly modulated PNN densities surrounding hippocampal neurons and the balance of excitatory and inhibitory synapses. These findings reveal key roles for CS 4-
O
-sulfation in adult brain plasticity, social memory, and anxiety regulation, and they suggest that targeting CS 4-
O
-sulfation may represent a strategy to address neuropsychiatric and neurodegenerative diseases associated with social cognitive dysfunction.
Cycloisomerization of Allene-Enol Ethers under Bi(OTf) 3 Catalysis. -Bi(OTf) 3 selectively promotes the activation of the enol ether moiety of the substrate accessing interesting functionalized cyclopentene rings. The method is extended to the synthesis of dihydrofuran and oxaspirocycle derivatives. -(ONDET, P.; JOFFRIN, A.; DIAF, I.; LEMIERE*, G.; DUNACH, E.; Org. Lett. 17 (2015) 4, 1002-1005, http://dx.doi.org/10.1021/acs.orglett.5b00110 ; Inst. Chim., Univ. Nice-Sophia-Antipolis, F-06108 Nice, Fr.; Eng.) -H. Toeppel 28-030
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