Introduction to the Symposium on Interstate Disputes Over Water Rights

Disagreements over the management and allocation of transboundary freshwater resources have become increasingly prominent in international relations. Serious diplomatic tensions surround management of the Jordan, Mekong, Nile, Rio Grande, Silala, Syr Darya and Amu Darya, and Tigris and Euphrates rivers, to name just the most prominent examples among the world’s more than three hundred shared watercourses. Nor is there any reason to think tensions will subside in the future. Whether disagreements over shared freshwater resources will continue to be resolved peacefully will depend, in part, on the viability, durability, and flexibility of international law to prevent and resolve such disputes. This symposium examines the role and relevance of international water law for peacefully resolving disputes over transboundary freshwater resources. The articles in this compilation provide an impressive breadth of approaches, from close examination of contemporary disputes over transboundary freshwater resources to the interpretation and application of specific IWL norms and principles. The articles also feature the perspectives of scholars from Africa, Asia, Europe, and North America

A new MR-SAD algorithm for the automatic building of protein models from low-resolution X-ray data and a poor starting model

Determining macromolecular structures from X-ray data with resolution worse than 3 Å remains a challenge. Even if a related starting model is available, its incompleteness or its bias together with a low observation-to-parameter ratio can render the process unsuccessful or very time-consuming. Yet, many biologically important macromolecules, especially large macromolecular assemblies, membrane proteins and receptors, tend to provide crystals that diffract to low resolution. A new algorithm to tackle this problem is presented that uses a multivariate function to simultaneously exploit information from both an initial partial model and low-resolution single-wavelength anomalous diffraction data. The new approach has been used for six challenging structure determinations, including the crystal structures of membrane proteins and macromolecular complexes that have evaded experts using other methods, and large structures from a 3.0 Å resolution F1-ATPase data set and a 4.5 Å resolution SecYEG–SecA complex data set. All of the models were automatically built by the method to Rfree values of between 28.9 and 39.9% and were free from the initial model bias

A new MR-SAD algorithm for the automatic building of protein models from low-resolution X-ray data and a poor starting model

Determining macromolecular structures from X-ray data with resolution worse than 3 Å remains a challenge. Even if a related starting model is available, its incompleteness or its bias together with a low observation-to-parameter ratio can render the process unsuccessful or very time-consuming. Yet, many biologically important macromolecules, especially large macromolecular assemblies, membrane proteins and receptors, tend to provide crystals that diffract to low resolution. A new algorithm to tackle this problem is presented that uses a multivariate function to simultaneously exploit information from both an initial partial model and low-resolution single-wavelength anomalous diffraction data. The new approach has been used for six challenging structure determinations, including the crystal structures of membrane proteins and macromolecular complexes that have evaded experts using other methods, and large structures from a 3.0 Å resolution F_1-ATPase data set and a 4.5 Å resolution SecYEG–SecA complex data set. All of the models were automatically built by the method to R_(free) values of between 28.9 and 39.9% and were free from the initial model bias

The Extracellular Regions of Adhesion G Protein-Coupled Receptors Regulate Ligand Binding and Intracellular Signaling

G protein-coupled receptors (GPCRs) have emerged as incredibly successful drug targets. Members of the adhesion GPCRs (aGPCR) family are characterized by diverse extracellular regions (ECRs), which play roles in cell adhesion, and mediate a subset of aGPCR functions in vivo. Though these receptors are implicated in myriad disease processes, there are no aGPCR-targeted therapeutics to date, due in large part to both the absence of well-behaving ligands as well as the technical challenges associated with mechanistic studies of aGPCR ECRs. We present a structural and functional study of the aGPCR GPR56/ADGRG1, a receptor critical for neurodevelopment and leukemia progression. To overcome many of the challenges mentioned above, we generated over thirty synthetic protein ligands, termed monobodies, that bind diverse epitopes across the ECR. Using a monobody crystallization chaperone, we solved the structure of the full ECR of GPR56, a first for any aGPCR, revealing the domain boundaries in the ECR as well as the identity and unique fold of the previously undefined N-terminal domain. We showed this domain regulates signaling and natural ligand binding in vitro, is deleted via alternative splicing, and mediates myelination in vivo. Additionally, we developed monobodies with stimulatory and inhibitory functions, demonstrating that ECR-targeted ligands can directly regulate aGPCR signaling, and are therefore valuable experimental reagents as well as lead-molecules for therapeutic development. Our results suggest an intricate, ECR-mediated molecular mechanism underlying aGPCR regulation. With the ultimate goal of combating aGPCR-mediated diseases, our findings will pave the way for targeted therapeutic development

Introduction to the Symposium on Interstate Disputes Over Water Rights

Disagreements over the management and allocation of transboundary freshwater resources have become increasingly prominent in international relations. Serious diplomatic tensions surround management of the Jordan, Mekong, Nile, Rio Grande, Silala, Syr Darya and Amu Darya, and Tigris and Euphrates rivers, to name just the most prominent examples among the world’s more than three hundred shared watercourses. Nor is there any reason to think tensions will subside in the future. Whether disagreements over shared freshwater resources will continue to be resolved peacefully will depend, in part, on the viability, durability, and flexibility of international law to prevent and resolve such disputes. This symposium examines the role and relevance of international water law for peacefully resolving disputes over transboundary freshwater resources. The articles in this compilation provide an impressive breadth of approaches, from close examination of contemporary disputes over transboundary freshwater resources to the interpretation and application of specific IWL norms and principles. The articles also feature the perspectives of scholars from Africa, Asia, Europe, and North America

A Comprehensive Mutagenesis Screen of the Adhesion GPCR Latrophilin-1/ADGRL1

Summary: Adhesion G-protein-coupled receptors (aGPCRs) play critical roles in diverse cellular processes in neurobiology, development, immunity, and numerous diseases. The lack of molecular understanding of their activation mechanisms, especially with regard to the transmembrane domains, hampers further studies to facilitate aGPCR-targeted drug development. Latrophilin-1/ADGRL1 is a model aGPCR that regulates synapse formation and embryogenesis, and its mutations are associated with cancer and attention-deficit/hyperactivity disorder. Here, we established functional assays to monitor latrophilin-1 function and showed the activation of latrophilin-1 by its endogenous agonist peptide. Via a comprehensive mutagenesis screen, we identified transmembrane domain residues essential for latrophilin-1 basal activity and for agonist peptide response. Strikingly, a cancer-associated mutation exhibited increased basal activity and failed to rescue the embryonic developmental phenotype in transgenic worms. These results provide a mechanistic foundation for future aGPCR-targeted drug design. : Molecular Biology; Membrane Architecture; Protein Structure Aspects Subject Areas: Molecular Biology, Membrane Architecture, Protein Structure Aspect