PB Marine Cyanobacteria 175Ramaswamy et al. 5 The Secondary Metabolites and Biosynthetic Gene Clusters of Marine Cyanobacteria. Applications in

Marine cyanobacteria have proven to be one of the most versatile marine producers of secondary metabolites. Many of these metabolites demonstrate antiproliferative activity (e.g. curacin A, dolastatins), acute cytotoxic activity (e.g. apratoxin, hectochlorin) or have specific neurotoxic activity (e.g. kalkitoxin, antillatoxin), making them invaluable as potential therapeutic leads or pharmacological tools. The predominant biogenetic theme in cyanobacterial natural products chemistry is the integration of polyketide synthases (PKS) and nonribosomal peptide synthetases (NRPS) along with a variety of unusual tailoring or modifying enzymes, and accounts for the tremendous structural diversity of their metabolites. Only recently has the genetic architecture of several cyanobacterial biosynthetic gene clusters been determined, and studies to understand and exploit this biosynthentic machinery present an exciting new frontier. This chapter will summarize the properties of several notable metabolites from marine cyanobacteria that have clinical or pharmacological applications followed by a detailed account of their biosyntheses at the molecular genetic level and their potential applications in biotechnology. 1