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Background: Invadopodia facilitate cancer cell extravasation, but the molecular mechanism whereby invadopodia-specific proteases such as MT1-MMP are called to invadopodia is unclear. Methods: Mass spectrometry and immunoprecipitation were used to identify interactors of MT1-MMP in metastatic breast cancer cells. After identification, siRNA and small molecule inhibitors were used to assess the effect these interactors had on cellular invasiveness. The chicken embryo chorioallantoic membrane (CAM) model was used to assess extravasation and invadopodia formation in vivo. Results: In metastatic breast cancer cells, MT1-MMP was found to associate with plectin, a cytolinker and scaffolding protein. Complex formation between plectin and MT1-MMP launches invadopodia formation, a subtype we termed iplectin (i = invadopodial). iPlectin delivers MT1-MMP to invadopodia and is indispensable for regulating cell surface levels of the enzyme. Genetic depletion of plectin with siRNA reduced invadopodia formation and cell invasion in vitro. In vivo extravasation efficiency assays and intravital imaging revealed iplectin to be a key contributor to invadopodia ultrastructure and essential for extravasation. Pharmacologic inhibition of plectin using the small molecule Plecstatin-1 (PST-1) abrogated MT1-MMP delivery to invadopodia and extravasation efficiency. Conclusions: Anti-metastasis therapeutic approaches that target invadopodia are possible by disrupting interactions between MT1-MMP and iplectin. Clinical Trial Registration Number: NCT04608357 [ABSTRACT FROM AUTHOR]

Weak intermolecular forces are typically very difficult to observe in highly competitive polar protic solvents as they are overwhelmed by the quantity of competing solvent. This is even more challenging for three‐component ternary assemblies of pure organic compounds. In this work, we overcome these complications by leveraging the binding of fused aromatic N‐heterocycles in an open resorcinarene cavity to template the formation of a three‐component halogen‐bonded ternary assembly in a protic polar solvent system. [ABSTRACT FROM AUTHOR]

Archaeal threonyl-tRNA synthetase (ThrRS) possesses an editing active site wherein tRNAThr that has been misaminoacylated with serine (i.e., Ser-tRNAThr) is hydrolytically cleaved to serine and tRNAThr. It has been suggested that the free ribose sugar hydroxyl of Ado76 of the tRNAThr (Ado762'OH) is the mechanistic base, promoting hydrolysis by orienting a nucleophilic water near the scissile Ser-tRNAThr ester bond. We have performed a computational study, involving molecular dynamics (MD) and hybrid ONIOM quantum mechanics/molecular mechanics (QM/MM) methods, considering all possible editing mechanisms to gain an understanding of the role played by Ado762'OH group. More specifically, a range of concerted or stepwise mechanisms involving four-, six-, or eight-membered transition structures (total of seven mechanisms) were considered. In addition, these seven mechanisms were fully optimized using three different DFT functionals, namely, B3LYP, M06-2X, and M06-HF. The M06-HF functional gave the most feasible energy barriers followed by the M06-2X functional. The most favorable mechanism proceeds stepwise through two six-membered ring transition states in which the Ado762'OH group participates, overall, as a shuttle for the proton transfer from the nucleophilic H2O to the bridging oxygen (Ado763'O) of the substrate. More specifically, in the first step, which has a barrier of 25.9 kcal/mol, the Ado762'-OH group accepts a proton from the attacking nucleophilic water while concomitantly transferring its proton onto the substrates C-Ocarb center. Then, in the second step, which also proceeds with a barrier of 25.9 kcal/mol, the Ado762'-OH group transfers its proton on the adjacent Ado763'-oxygen, cleaving the scissile Ccarb-O3'Ado76 bond, while concomitantly accepting a proton from the previously formed C-OcarbH group. [ABSTRACT FROM AUTHOR]

The bisoxazole containing natural product O-methyl siphonazole was assembled using a suite of microreactors via a flowbased approach in concert with traditional batch methods. The use of a toolbox of solid-supported scavengers and reagents to aid purification afforded the natural product in a total of nine steps. [ABSTRACT FROM AUTHOR]

The heavier chalcogens sulfur and selenium are important in organic and inorganic chemistry, and the role of such chalcogens in biological systems has recently gained more attention. Sulfur and, to a lesser extent selenium, are involved in diverse reactions from redox signaling to antioxidant activity and are considered essential nutrients. We investigated the ability of the DFT functionals (B3LYP, B3PW91, ωB97XD, M06-2X, and M08-HX) relative to electron correlation methods MP2 and QCISD to produce reliable and accurate structures as well as thermochemical data for sulfur/selenium-containing systems. Bond lengths, proton affinities (PA), gas phase basicities (GPB), chalcogen–chalcogen bond dissociation enthalpies (BDE), and the hydrogen affinities (HA) of thiyl/selenyl radicals were evaluated for a range of small polysulfur/selenium compounds and cysteine per/polysulfide. The S–S bond length was found to be the most sensitive to basis set choice, while the geometry of selenium-containing compounds was less sensitive to basis set. In mixed chalcogens species of sulfur and selenium, the location of the sulfur atom affects the S–Se bond length as it can hold more negative charge. PA, GPB, BDE, and HA of selenium systems were all lower, indicating more acidity and more stability of radicals. Extending the sulfur chain in cysteine results in a decrease of BDE and HA, but these plateau at a certain point (199 kJ mol−1 and 295 kJ mol−1), and PA and GPB are also decreased relative to the thiol, indicating that the polysulfur species exist as thiolates in a biological system. In general, it was found that ωB97XD/6-311G(2d,p) gave the most reasonable structures and thermochemistry relative to benchmark calculations. However, nuances in performance are observed and discussed. [ABSTRACT FROM AUTHOR]

Weak intermolecular forces are typically very difficult to observe in highly competitive polar protic solvents as they are overwhelmed by the quantity of competing solvent. This is even more challenging for three-component ternary assemblies of pure organic compounds. In this work, we overcome these complications by leveraging the binding of fused aromatic N-heterocycles in an open resorcinarene cavity to template the formation of a three-component halogen-bonded ternary assembly in a protic polar solvent system., (© 2023 Wiley-VCH GmbH.)

Archaeal threonyl-tRNA synthetase (ThrRS) possesses an editing active site wherein tRNA Thr that has been misaminoacylated with serine (i.e., Ser-tRNA Thr ) is hydrolytically cleaved to serine and tRNA Thr . It has been suggested that the free ribose sugar hydroxyl of Ado76 of the tRNA Thr ( Ado76 2'OH) is the mechanistic base, promoting hydrolysis by orienting a nucleophilic water near the scissile Ser-tRNA Thr ester bond. We have performed a computational study, involving molecular dynamics (MD) and hybrid ONIOM quantum mechanics/molecular mechanics (QM/MM) methods, considering all possible editing mechanisms to gain an understanding of the role played by Ado76 2'OH group. More specifically, a range of concerted or stepwise mechanisms involving four-, six-, or eight-membered transition structures (total of seven mechanisms) were considered. In addition, these seven mechanisms were fully optimized using three different DFT functionals, namely, B3LYP, M06-2X, and M06-HF. The M06-HF functional gave the most feasible energy barriers followed by the M06-2X functional. The most favorable mechanism proceeds stepwise through two six-membered ring transition states in which the Ado76 2'OH group participates, overall, as a shuttle for the proton transfer from the nucleophilic H 2 O to the bridging oxygen ( Ado76 3'O) of the substrate. More specifically, in the first step, which has a barrier of 25.9 kcal/mol, the Ado76 2'-OH group accepts a proton from the attacking nucleophilic water while concomitantly transferring its proton onto the substrates C-O carb center. Then, in the second step, which also proceeds with a barrier of 25.9 kcal/mol, the Ado76 2'-OH group transfers its proton on the adjacent Ado76 3'-oxygen, cleaving the scissile C carb -O3' Ado76 bond, while concomitantly accepting a proton from the previously formed C-O carb H group.

The cycloaddition of acetylenes with azides to give the corresponding 1,4-disubstituted 1,2,3-triazoles is reported using immobilised reagents and scavengers in pre-packed glass tubes in a modular flow reactor.