Van Anh Ngo

β-Arrestins are multifunctional regulators of G-protein-coupled receptor (GPCR) signalling and orchestrate diverse downstream signalling events and physiological responses across the GPCR superfamily ^1–3 . Although GPCR pharmacology has advanced to target orthosteric and allosteric sites, as well as G proteins and GPCR kinases, direct chemical tools to modulate β-arrestin activities have remained conspicuously absent. Here we report the identification of small-molecule inhibitors that selectively target β-arrestins and delineate their mechanism of action through integrated pharmacological, biochemical, biophysical and structural analyses. These inhibitors disrupt β-arrestin engagement with agonist-activated GPCRs, impairing desensitization, internalization and β-arrestin-dependent physiological functions while sparing G protein–receptor coupling. Cryo-electron microscopy, molecular dynamics simulations and structure-guided mutagenesis reveal that one modulator, Cmpd-5, engages a pocket within the central crest of β-arrestin1 formed by the middle, C and lariat loops, a critical receptor-binding interface, stabilizing a distinct conformation that is incompatible with full β-arrestin–receptor engagement. Together, these findings establish a mechanistic framework for β-arrestin modulation, reveal a novel allosteric site for structure-based drug design, and open new avenues for transducer-targeted, pathway-specific GPCR therapeutic agents.

Fusarium oxysporum is a fungal plant pathogen for over 100 agricultural crop species. There are strategies for managing Fusarium wilt, including antagonistic bacteria that offer a promising and sustainable effect. In this work, among the various endophytic bacterial strains, Paenibacillus polymyxa EB.KN35 was selected as the best antifungal strain against F. oxysporum. For eco-friendly biomass production of this bacterium, some agricultural byproducts were tested for cultivation, and a soybean processing byproduct (SPBP) was found to be a suitable C/N source for P. polymyxa EB.KN35 fermentation. The utilization of a 14 L bioreactor system for P. polymyxa EB.KN35 fermentation achieved a high biomass productivity (3.46 × 10¹¹ CFU/mL) in a short time (8 h). In bioactive compound analysis, EB.KN35 was found to be secreting several plant growth-promoting compounds such as GA3, IAA, kinetin, and zeatin (via HPLC) and eleven volatile compounds (via GC–MS). The docking study indicated that some volatile compounds (1, 2, 4, and 9) may play a significant role in inhibiting F. oxysporum. The study results highlight the potential for reusing a soybean processing byproduct as a C/N source for the bioproduction of P. polymyxa EB.KN35 with potential use as a biocontrol agent and biofertilizer.

β-arrestins are multifunctional regulators of G protein-coupled receptor (GPCR) signaling, orchestrating diverse downstream signaling events and physiological responses across the vast GPCR superfamily. While GPCR pharmacology has advanced to target orthosteric and allosteric sites, as well as G proteins and GRKs, comparable chemical tools to study β-arrestins remain lacking. Here, we report the discovery of small-molecule inhibitors that selectively target β-arrestins and delineate their mechanism of action through integrated pharmacological, biochemical, biophysical, and structural analyses. These inhibitors disrupt β-arrestin-engagement with agonist-activated GPCRs, impairing desensitization, internalization, and β-arrestin-dependent functions while sparing G protein–receptor coupling. Cryo-EM, MD simulations, and structure-guided mutagenesis reveal that one modulator, Cmpd-5, engages a cryptic pocket formed by the middle, C-, and lariat loops of β-arrestin1—a critical receptor-binding interface—stabilizing a distinct conformation incompatible with GPCR engagement. Together, these findings provide a mechanistic framework for β-arrestin modulation, introducing transducer-targeted strategies to fine-tune GPCR signaling and guide the development of pathway-specific therapeutics.

The U.S. Department of Energy's Office of Scientific and Technical Information

Phytophthora palmivora là nấm gây bệnh chủ yếu gây chết cây sầu riêng hiện nay. Nghiên cứu đã tiến hành phân lập, tuyển chọn và nhân nuôi các chủng vi khuẩn nội sinh kháng nấm P.palmivora. Sử dụng phương pháp phân lập Endophytic bacteria từ 12 mẫu sầu riêng tại huyện Cư Kuin đã dòng hoá được 29 chủng. Hoạt tính đối kháng của vi khuẩn nội sinh với P. palmivora được thực hiện bằng phương pháp đồng nuôi cấy, các điều kiện nhân nuôi Endophytic bacteria được đánh giá trong in vitro. Tuyển chọn được 11 chủng có khả năng đối kháng P. palmivora với hiệu lực đối kháng khoảng 50,62 - 67,41%, chủng EB.CK9 có khả năng kháng P. palmivora cao nhất (67,41%) được xác định là B. amyloliquefaciens dựa trên phương pháp giải trình tự gen 16S rRNA. Kết quả nhân nuôi trong bình tam giác, chủng EB.CK9 sinh trưởng tốt nhất ở 36oC, pH=7, 200rpm, sau 48h đạt 44,5 x108 CFU/ml. Sản xuất chế phẩm B. amyloliquefaciens EB.CK9 trong hệ thống Bioreactor 14 L đạt mật độ 8,25x1011 CFU/ml sau 10h lên men. Nghiên cứu mở ra hướng ứng dụng phát triển chế phẩm sinh học bản địa từ vi khuẩn nội sinh nhằm canh tác hiệu quả và bền vững sầu riêng.

Our study reveals the underlying principles governing the passive membrane permeability in three large N-methylated macrocyclic peptides (N-MeMPs): cyclosporine A (CycA), Alisporivir (ALI), and cyclosporine H (CycH). We determine a series of conformers required for robust passive membrane diffusion and those relevant to other functions, such as binding to protein targets or intermediates, in the presence of solvent additives. We investigate the conformational interconversions and establish correlations with the membrane permeability. Nuclear magnetic resonance (NMR) and cyclic ion-mobility spectrometry-mass spectrometry (cIMS-MS) are employed to characterize conformational heterogeneity and identify cis-amides relevant for good membrane permeability. In addition, ion mobility selected cIMS-MS and infrared (IR) multiple-photon dissociation (IRMPD) spectroscopy experiments are conducted to evaluate the energy barriers between conformations. We observe that CycA and ALI, both cyclosporines with favorable membrane permeabilities, display multiple stable and well-defined conformers. In contrast, CycH, an epimer of CycA with limited permeability, exhibits fewer and fewer stable conformers. We demonstrate the essential role of the conformational shift from the aqueous cis MeVal11–MeBmt1 state (A1) to the closed conformation featuring cis MeLeu9–MeLeu10 (C1) in facilitating membrane permeation. Additionally, we highlight that the transition from A1 to the all-trans open conformation (O1) is specifically triggered by the presence of CaCl₂. We also capture a set of conformers with cis Sar3–MeLeu4, MeLeu9–MeLeu10, denoted as I. Conformationally selected cIMS-MS and IRMPD data of [CycA+Ca]²⁺ show immediate repopulation of the original population distribution, suggesting that CaCl₂ smooths out the energy barriers. Finally, our work presents an improved sampling molecular dynamics approach based on a refined force field that not only consistently and accurately captures established conformers of cyclosporines but also exhibits strong predictive capabilities for novel conformers.