Macromolecular structure information and databases

PROGRESS IN GENETIC engineering, X-ray crystallography and Nuclear Magnetic Resonance (NMR) spectroscopy, and the advent of cheap and powerful computers, have brought about an exponential growth of data on macromolecular three-dimensional structures. Although the number of protein structures known today (approximately 3500) is still well below that of protein sequences (over 50 000), its growth rate parallels that observed for protein sequences several years ago and continues to rise, with an expected 30000 known structures by the turn of this century. The expected number of nucleic acid structures is smaller, but will also rise steadily. Managing the information on biomacromolecule sequences and structures has become one of the major challenges of modern molecular biology. This is particularly difficult in the case of protein three-dimensional structures, because it is necessary to handle a wealth of complex information, some of which must be derived (or calculated) from the atomic coordinates by applying specialized programs (Box 1). Furthermore, the data must be validated, i.e. the quality and the consistency of the data must be assessed. To promote scientific progress, structural information must also be integrated with other data, such as that on function, gene structure and phylogeny, which are obtained from other sources or stored in different databanks. In addition, the data must be easily and widely accessible to the molecular biology community. Meeting this challenge requires that the ways of storing, cross-