This role, and that of the associated Nucleic Acid Database (NDB), is discussed in more detail at the end of this review. This article aims to highlight some of the major steps in our knowledge of DNA structure because the advent of the double helix concept and how the PDB has, in various ways, played a key role in actively facilitated these advances. For DNA structural studies, the PDB is, though, much more than a passive depository of structures to be uploaded or downloaded as needed. For any new structure, comparative studies with existing structures are an essential part of any meaningful analysis, and the PDB has long provided the data and tools for these to be undertaken. All crystal and NMR structures are deposited in the PDB and released for open access, normally either before to or immediately after publication. It is inconceivable that any structural studies on DNAs over the past 50 years would have taken place without the involvement of the Protein Data Bank (PDB) at some point. KeywordsĪbbreviations: NDB ( Nucleic Acid Database), PDB ( Protein Data Bank) 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 Protein Data Bank by for example, data mining, has illuminated DNA structural concepts. The Protein Data Bank 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 to facilitate analysis of conformational and base morphology features. Yet more complex folds can result in DNAs with extended tertiary structures and enzymatic/catalytic activity. 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. 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. 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, and to left-handed duplex DNAs. This structure has also been the starting point for the determination of some 2000 DNA crystal structures in the subsequent 68 years. The determination of the double helical structure of DNA in 1953 remains the landmark event in the development of modern biological and biomedical science. Glycobiology and Extracellular Matrices.
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