From black boxes to defined structure–function relationships

Abstract

Current Topics in Microbiology and Immunology Vol. 257: Pore-forming Toxinsedited by F. Gisou van der GootSpringer-Verlag, 2001.£55.50 (hbk) (166 pages)ISBN 3 540 41386 3One of the recent additions to the Current Topics in Microbiology and Immunology series is a volume on pore-forming toxins. At first glance, it seems that many bacterial pore-forming toxins are well characterized and appear to act on target cells by defined mechanisms. Often, when the structure of a bacterial toxin is well known and its mode of action has been described in some detail, the toxin starts to get boring for basic scientists. Thus, are the pore-forming toxins described in this volume boring? By no means! On reading this volume, it is clear that research into bacterial pore-forming toxins is in an exciting phase. This notion is underlined by recent discoveries, for example, the finding that the pore-forming toxin streptolysin O acts in concert with the Streptococcus pyogenes NAD-glycohydrolase to translocate the enzyme into the target cell in a Gram-positive equivalent of type III secretion [1xCytolysin-mediated translocation (CMT): a functional equivalent of type III secretion in Gram-positive bacteria. Madden, J.C. et al. Cell. 2001; 104: 143–152Abstract | Full Text | Full Text PDF | PubMed | Scopus (176)See all References][1].This volume contains chapters on cholesterol-dependent cytolysins; aerolysin and related toxins; staphylococcal pore-forming toxins; RTX toxins; the vacuolating cytotoxin (VacA) from Helicobacter pylori; and the large family of pore-forming colicins. Although mentioned in the introduction, the insecticidal pore-forming toxins from Bacilli are omitted. I also missed a chapter on binary toxins, which use their pore-forming ability primarily to transport enzyme components such as the protective antigen (PA) of anthrax toxin or the binding components of actin-modifying toxins. It would have been interesting to compare pore formation by these toxins with that of the classical members of the pore-forming toxin family; in this respect, H. pylori VacA does not appear to be a classical pore-forming toxin and other functions might be responsible for its cytotoxicity.Each chapter is well organized, written by experts in the field and presents a detailed account of the latest state-of-the-art research. The chapters cover structural details, including crystal structures when available, domain analyses of the toxins and their assembly, the nature of their membrane receptors, mechanisms of pore formation and, finally, the role of the toxins in pathogenesis. The chapters answer many questions and provide lots of new information. In many cases, simple, but once elusive, schematics and figures are added. However, future Editors of the series must think about improving the quality of the figures (e.g. by using colour) and showing relevant crystal structures (additionally, notes on the availability of information on the internet should be added). Taken together, this volume will be especially helpful for young scientists who are not directly involved in research into bacterial pore-forming toxins and need to acquire comprehensive knowledge about this particular field quickly. In this respect, the clarification of the nomenclature found in various chapters is also important.I particularly enjoyed the chapter on RTX toxins, which emphasizes new aspects and controversial interpretations of the available toxin data. This chapter, in common with many others, raises more questions than it answers, thus reflecting the exciting nature of this field of research.