Streptomycetes are bacteria known to inhabit the soil and marine ecosystems worldwide. Within their niches streptomycetes have developed complex and efficient mechanisms of defense against other organisms through the production of anti-bacterial, anti-fungal and anti-nematode compounds and other bioactive compounds, many of which have value in human and veterinary medicine. Streptomycetes also exhibit a broad-based ability to detoxify organic poisons. Both these defense systems involve monooxygenases of the cytochrome P450 (CYP) superfamily representing about 0.25% of streptomycete genes. Many of the CYP gene families overlap between Streptomyces spp. as judged by genomic data, but different subfamilies and families are apparent that reflect the different needs in secondary metabolism. The diversity of P450s reflects the selective pressures allowing subtly different activities to evolve and be retained and a long term goal of this project is to understand general features of substrate-binding to streptomycete P450s and strategies used in different species to redesign P450 primary sequence leading to different natural products. This information will establish a knowledge base from which we can consider the production of new and potent bioactive compounds. The genome of Streptomyces coelicolor A3 (2) contains 18 CYP genes and this current application proposes to establish the function of eight of these CYPs selected from our lead-up work, to correlate their high resolution X-ray structure with function, and to generate modified forms of these CYPs by mutagenesis to examine altered biological activity. S. coelicolor is a particularly good system for this study because a large number of its secondary metabolites are known and they represent a diverse group of organic molecules, but also due to the facile molecular systems established for study of this species. Further, most of the CYPs fall into small groups of related enzymes (same family or subfamily). Three laboratories with overlapping expertise and ongoing collaborations have joined forces to achieve these goals. When complete, this study of CYPs from S. coelicolor will set the stage for alteration of other Streptomyces spp. which through modified defense systems can produce new antibiotics and other drugs for human and animal medicine.
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