Special issue on structural biology.

Welcome to the special structural biology issue of the Journal of Bacteriology! We have all heard the adage that a picture is worth a thousand words. Well, from each structure, hundreds of pictures can be produced. Structural biology gives the framework to understand disparate observations and to make new hypotheses. It keeps us from missing the big picture. By seeing how the peptide backbone folds, we learn which residues are close in space although they may be distant in primary sequence. We can also see residues that may be important for establishing a fold versus those that are important for recognizing a substrate. Over the past 50 years, some of the most important insights in molecular biology—the double helix, the photosynthetic reaction center, the ribosome—have come from structural analysis. Although structural papers have occasionally been published in JB, it was realized that this important area of investigation was inadequately represented in the journal. For this reason an initiative has developed to get more structural biologists to send their papers to JB, and I was brought in as an editor to lead this effort. JB has long been a leading high-impact journal dealing with the biology of prokaryotes. Its readership is very broad and includes biologists interested in topics as diverse as cell biology, genetics, and pathogenesis and biochemists interested in molecular mechanisms (such as signal transduction), enzymology, and metabolism. For this reason, JB is a natural vehicle for research results from scientists studying all aspects of prokaryotic biology. During the final decades of the 20th century, knowledge regarding the genomes of organisms exploded. Naturally, it is the prokaryotic genomes that have led the way, with 108 (96 bacterial and 12 archaeal) prokaryote genomes currently completed. Now we are moving from genomics to proteomics, which focuses on what the products of those genes do. Sometimes this can be deduced on the basis of sequence homology. However, about one-third of the revealed open reading frames show homology to other open reading frames of unknown function or show no significant homology at all. Here, structural analysis can be used to reveal structural homologs or possible active sites whose shapes can, in turn, suggest activity. Technology has aided in structural studies, with the use of synchrotron radiation for multiwavelength anomalous dispersion phasing, the building of more powerful nuclear magnetic resonance instruments with cryo stages, and the development of low-dose imaging techniques for electron microscopy making structures more accessible. No longer do structures require many man-years of effort. New structures today, under the most favorable conditions, can be revealed in days, if not hours! This sea change has led to new initiatives such as that in the area of structural genomics (http://www.nigms.nih.gov/funding/psi.html). As we face the explosion of structures coming in the 21st century, it is still the prokaryotes that are leading the way. From these data we will gain an understanding of basic biological processes. For pathogens, new modes for developing therapeutics will be revealed. For archaea, we will learn how some of the most difficult chemistry is accomplished under extreme conditions. With this issue, JB is stepping forward to assume a leading role in the area of the structural biology of prokaryotes. We invite your participation through the submission of new, exciting results by researchers and by the appraisal of these results by readers.