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Abstract: A simple dipeptide WR (tryptophan–arginine) in the form of salts with organic acids tartaric acid or crotonic acid is shown to form glasses through a benign preparation route by evaporation of aqueous solution. The glasses have a remarkable range of properties including moldability, high transparency across a broad range of wavelengths, and fluorescence. The glasses show self-healing and adhesive properties, and have accessible glass transition temperatures. The glasses are shown to be amorphous via small-angle and wide-angle X-ray scattering (SAXS/WAXS) and scanning electron microscopy (SEM). Remarkably, the glasses are found to have a chiral structure, as shown by circular dichroism (CD) spectroscopy. Investigation of glass precursor dipeptide salt solutions shows that the glasses form from an initial unordered solution containing chiral peptide molecules. The diverse properties of the dipeptide glass materials points to a wide range of potential future applications.

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Abstract: Multicomponent peptide nanostructures offer a powerful platform for designing functional materials, yet controlling their co-assembly remains a key challenge. Here, we harness electrostatic molecular recognition to drive the selective co-assembly of five amphiphilic ionic peptide binary mixtures (M1–M5). Our results revealed that charge distribution governs β-sheet strand alignment (parallel vs. antiparallel), assembly kinetics, and hydrogel viscoelasticity. Mixing stoichiometry and pH significantly influences co-assembly behavior, nanofiber morphology, and network structure (self-sorted vs. hetero-aggregated). At pH 7, equimolar mixtures undergo nucleation-driven co-assembly into hetero-aggregates, immediately forming well-defined nanofibers, while non-equimolar ratios yield altered morphologies. At a slightly acidic pH of 5–7, both E and K side chains are charged, enabling complementary ionic interactions that promote co-assembly and gelation. Outside this pH range, co-assembly is impaired. Notably, M1 forms β-sheets and hydrogels at acidic pH (≤4) via independent self-assembly of its components, suggesting self-sorted fibers. Overall, we demonstrate that tuning charge complementarity, ionization state, and stoichiometry enables precise control over the molecular, nanoscale, and mechanical properties of multicomponent peptide assemblies, providing a framework for the rational design of advanced peptide-based materials.

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Abstract: Candida glabrata is the second leading cause of mortality in immunocompromised patients hospitalized for invasive candidiasis (IC). Several drugs have been available to treat this disease for decades, such as polyenes, azoles, echinocandins, flucytosine, and, in critical cases, amphotericin B. However, these antifungals’ constant and routine use have led to the development of resistance mechanisms, making the design and development of new drugs indispensable. The first step for the design and subsequent synthesis of a new chemical molecule as a potential antifungal is the identification of new therapeutic targets. In that pathway, our working group has identified moonlight-like cell wall proteins (CWPs) in different Candida species that can act as potential antifungal targets. One of these moonlight-like CWPs is phosphoglycerate kinase (Pgk) from C. glabrata. Once Pgk was identified as a potential therapeutic target in different human pathogens, the first step to perform drug design against this moonlight-like CWP was the elucidation of the three-dimensional (3D) structure since the 3D structure is key to understanding the interactions between a drug candidate and its target at the molecular level. In the present work, we aimed to elucidate the 3D structure of C. glabrata Pgk. To elucidate the 3D structure of this protein, the recombinant protein was expressed, purified, and structurally resolved by means of a structural analysis by small-angle X-ray scattering (SAXS). Additionally, in order to evaluate its potential as a therapeutic target, we have performed molecular docking studies and enzymatic activity assays with pure Pgk using known antifungals amphotericin B, nystatin, and fluconazole and with the new plausible drugs, such as nilotinib and netupitant. Our results showed some similarities and differences with orthologous Pgk proteins from other organisms, which was expected since Pgk has been observed to have evolved in the kingdoms of life. Molecular docking studies showed that Pgk interacts with all of the compounds tested. In enzyme activity assays, a change in the kinetic parameter Km on the enzyme Pgk was observed in response to its interaction with nilotinib, netupitant, and amphotericin B. Thus, our results allow us to propose Pgk from C. glabrata as a possible therapeutic target against candidiasis. We consider it essential to design and develop new molecules specifically targeting this enzyme, which will contribute to a decrease in mortality associated with IC and improve the patient’s quality of life.

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Abstract: The self-assembly in aqueous solution and conformation of lipopeptides C16-WKK, C16-KWK, C16-YKK and C16-KYK is compared and examined. Remarkable differences are observed among the systems despite the small sequence changes comparing C16-XKK with the C16-KXK homologue (X = W or Y), depending on pH. These are rationalized using a molecular theory for amphiphile self-assembly (MOLT) to predict the morphology along with atomistic molecular dynamics simulations to probe local conformation and packing, along with new experimental data from small-angle X-ray scattering (SAXS) and FTIR spectroscopy. MOLT correctly describes the high-pH morphology behavior, i.e., fibrils for C16-XKK, and lamellar nanotapes for C16-KXK, although it predicts micelles for all systems at low pH, whereas experiments indicate that this only occurs for the C16-XKK lipopeptides, not the C16-KXK, which form lamellar nanotapes stable over an extended range of pH 2–12. Atomistic MD reveals β-sheet conformation is more favored for the C16-XKK lipopeptides which also have enhanced aggregation propensity compared to C16-KXK analogues. The extent of π-stacking was higher for the latter lamellar nanotape structures. The extent of hydrogen bonding is higher for the tyrosine-containing molecules than the tryptophan-based ones. The combination of a molecular theory and atomistic MD provides a comprehensive insight into the remarkable sequence- and pH-dependent molecular ordering within these model lipopeptides which will enable the rational design of future peptide amphiphiles with targeted nanostructures for desired applications.

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Abstract: Microtubules have long been recognized as upstream mediators of intracellular signaling, but the mechanisms underlying this fundamental function remain elusive. Here, we identify the structural basis by which microtubules regulate the guanine nucleotide exchange factor H1 (GEFH1), a key activator of the Ras homolog family member A (RhoA) pathway. We show that specific features of the microtubule lattice bind the C1 domain of GEFH1, leading to the sequestration and inactivation of this signaling protein. Targeted mutations in C1 residues disrupt this interaction, triggering GEFH1 release and activation of RhoA-dependent immune responses. Building on this sequestration-and-release mechanism, we identify microtubule-binding C1 domains in additional signaling proteins, including other guanine nucleotide exchange factors (GEFs), kinases, a GTPase-activating protein (GAP), and a tumor suppressor, and show that microtubule-mediated regulation via C1 domains is conserved in the Ras association domain-containing protein 1A (RASSF1A). Our findings establish a structural framework for understanding how microtubules can function as spatiotemporal signal sensors, integrating and processing diverse signaling pathways to control important cellular processes.