Gauthierpayne9206

The determination of the double helical structure of DNA in 1953 remains the landmark event in the development of modern biological and biomedical science. This structure has also been the starting point for the determination of some 2000 DNA crystal structures in the subsequent 67 years. Their structural diversity has extended to the demonstration of sequence-dependent local structure in duplex DNA, to DNA bending in short and long sequences and in the DNA wound round the nucleosome, to left-handed duplex DNAs. Beyond the double helix itself, in circumstances where DNA sequences are or can be induced to unwind from being duplex, a wide variety of topologies and forms can exist. Quadruplex structures, based on four-stranded cores of stacked G-quartets, are prevalent though not randomly distributed in the human and other genomes, and can play roles in transcription, translation and replication. Yet more complex folds can result in DNAs with extended tertiary structures and enzymatic/catalytic activity. The PDB is the depository of all these structures and the resource where structures can be critically examined and validated, as well as compared one with another in order to facilitate analysis of conformational and base morphology features. This review will briefly survey the major structural classes of DNAs and illustrate their significance, together with some examples of how the use of the PDB by for example, data mining, has illuminated DNA structural concepts.Some of the amazing contributions brought to the scientific community by the PDB are described. The focus is on nucleic acid structures with a bias towards RNA. The evolution and key roles in science of the PDB and other structural databases for nucleic acids illustrate how small initial ideas can become huge and indispensable resources with the unflinching willingness of scientists to cooperate globally. The progress in the understanding of the molecular interactions driving RNA architectures followed the rapid increase in RNA structures in the PDB. That increase was consecutive to improvements in chemical synthesis and purification of RNA molecules, as well as in biophysical methods for structure determination and computer technology. The RNA modeling efforts from the early beginnings are also described together with their links to the state of structural knowledge and technological development. Structures of RNA and of its assemblies are physical objects which, together with genomic data, allow us to integrate present-day biological functions and the historical evolution in all living species on earth.The structural study of icosahedral viruses has a long and impactful history in both crystallographic methodology and molecular biology. The evolution of the Protein Data Bank has paralleled and supported these studies providing readily accessible formats dealing with novel features associated with viral particle symmetries and subunit interactions. This overview describes the growth in size and complexity of icosahedral viruses from the first early studies of small RNA plant viruses and human picorna viruses up to the larger and more complex bacterial phage, insect and human disease viruses such as Zika, hepatitis B, Adeno and Polyoma virus. The analysis of icosahedral viral capsid protein domain folds has shown striking similarities, with the beta jelly roll motif observed across multiple evolutionarily divergent species. The icosahedral symmetry of viruses drove the development of non-crystallographic symmetry averaging as a powerful phasing method, and the constraints of maintaining this symmetry resulted in the concept of quasi-equivalence in viral structures. Monocrotaline supplier Symmetry also played an important early role in demonstrating the power of cryo-electron microscopy as an alternative to crystallography in generating atomic resolution structures of these viruses. The Protein Data Bank has been a critical resource for assembling and disseminating these structures to a wide community, and the virus particle explorer (VIPER) was developed to enable users to easily generate and view complete viral capsid structures from their asymmetric building blocks. Finally, we share a personal perspective on the early use of computer graphics to communicate the intricacies, interactions and beauty of these virus structures.Structures deposited in the PDB facilitate our understanding of many biological processes including those that fall under the general category of glycobiology. However, structure-based studies of how glycans affect protein structure, how they are synthesized and how they regulate other biological processes remain challenging. Despite the abundant presence of glycans on proteins and the dense layers of glycans that surround most of our cells, structures containing glycans are underrepresented in the PDB. There are sound reasons for this, including difficulties in producing proteins with well-defined glycosylation and the tendency of mobile and heterogeneous glycans to inhibit crystallization. Nevertheless, the structures we do find in the PDB, even some of the earliest deposited structures, have had an impact on our understanding of function. I highlight a few examples in this review and point to some promises for the future. Promises include new structures from methodologies, such as cryo-EM, that are less affected by the presence of glycans and experiment-aided computational methods that build on existing structures to provide insight into the many ways glycans affect biological function.This essay, which was written to commemorate the 50th anniversary of the Protein Data Bank, opens with some comments about the intentions of the scientists who pressed for its establishment, and the nature of services it provides. It includes a brief account of the events that resulted in the determination of the crystal structure of the large ribosomal subunit from Haloarcula marismortui. The magnitude of the challenge the first ribosome crystal structures posed for the PDB is commented upon, and in the description of subsequent developments in the ribosome structure field that follows, it is pointed out that cryo-EM has replaced X-ray crystallography as the method of choice for investigating ribosome structure.