Laboratory of Molecular Bacteriology (Rega Institute)
1.Streptomyces as host for heterologous protein production. It has aldready proven that Streptomyces is a good choice for heterologous protein production and can be an invaluable host for eukaryotic proteins. Some of these heterologous proteins are secreted as biologically active compounds in commercially significant yield using expression/secretion signals we have isolated (EP0851931A), they can easily be purified and have the same characteristics as the native proteins. A number of 'bottlenecks' that hamper secretion of several proteins has still to be identified to develop a robust Streptomyces secretion system for the production of pharmaceutically relevant heterologous proteins. The main objectives of the research group are to investigate the potential of the Sec-dependent and the recently detected twin-arginine translocation (Tat) system to secrete heterologous proteins of biopharmaceutical relevance. Since protein recovery accounts for a considerable proportion of the bioprocess production overhead, this development has the potential to significantly reduce the resource commitment made to recover bioactive therapeutically relevant proteins. 2. Clostridium as a tumour-selective vector system for anticancer compounds. Clostridium are obligate anaerobes. Their spores are unable to germinate unless they encounter the requisite anaerobic conditions. Normal tissues in the body are well- oxygenated, whereas solid tumours contain hypoxic regions allowing Clostridiumto germinate. As a consequence, intravenously injected Clostridium spores germinate in the hypoxic region of solid tumours. This process is exquisitely selective, as the spores are demonstrably incapable of germinating in normal healthy tissues. Furthermore, it is now possible to engineer Clostridium to produce therapeutic proteins such as tumour necrosis factor alpha or prodrug activating enzymes bringing about the conversion of a secondary agent into a tumourogenic killing agent. Clostridium can thus be used as a highly selective in situ cell factory to produce and secrete antitumour therapeutics specifically at the tumour site. This makes Clostridium an alternative to the gene therapeutic approach to treat cancer. 3. The INFECTIOUS DISEASES RESEARCH GROUP focuses on virulence factors in medically important pathogens. We are particularly interested in Streptococcus pneumoniae and Staphylococcus. For Staphylococcus aureus we are investigating the factors involved in the adhesion of the bacteria to the nasal epithelium. To do this we have developed in vitro models of this epithelium. We have also developed an in vitro model of foreign body infections, in which we are investigating the expression of genes that alow colonisation of foreign material by coagulase-negative staphylococci. Foreign body infections are an important problem in modern medicine. For S. pneumoniae we are also focusing on the factors that allow colonisation of the respiratory mucosa by this pathogen. We have developed an in vitro cell-culture model that allows us to investigate this in a quantitative way.