Findings in life sciences reported from M. Mueller and co-researchers.

"Pore-forming toxins (PFTs) are a class of potent virulence factors that convert from a soluble form to a membrane-integrated pore(1). They exhibit their toxic effect either by destruction of the membrane permeability barrier or by delivery of toxic components through the pores," scientists in Zurich, Switzerland report (see also Life Sciences).

"Among the group of bacterial PFTs are some of the most dangerous toxins, such as diphtheria and anthrax toxin. Examples of eukaryotic PFTs are perforin and the membrane-attack complex, proteins of the immune system(2). PFTs can be subdivided into two classes, alpha-PFTs and beta-PFTs, depending on the suspected mode of membrane integration, either by alpha-helical or beta-sheet elements(3). The only high-resolution structure of a transmembrane PFT pore is available for a beta-PFT-alpha-haemolysin from Staphylococcus aureus 4. Cytolysin A (ClyA, also known as HlyE), an alpha-PFT, is a cytolytic alpha-helical toxin responsible for the haemolytic phenotype of several Escherichia coli and Salmonella enterica strains(5-8). ClyA is cytotoxic towards cultured mammalian cells, induces apoptosis of macrophages and promotes tissue pervasion(9-11). Electron microscopic reconstructions demonstrated that the soluble monomer of ClyA(12) must undergo large conformational changes to form the transmembrane pore(13,14). Here ...