title: Type III polyketide synthases in natural product biosynthesis.
abstract: Polyketides represent an important class of biologically active and structurally diverse compounds in nature. They are synthesized from acyl-coenzyme A substrates by polyketide synthases (PKSs). PKSs are classified into three groups: types I, II, and III. This article introduces recent studies on type III PKSs identified from plants, bacteria, and fungi, and describes the catalytic functions of these enzymes in detail. Plant type III PKSs have been widely studied, as exemplified by chalcone synthase, which plays an important role in the synthesis of plant metabolites. Bacterial type III PKSs fall into five groups, many of which were identified from Streptomyces, a genus that has been well known for its production of bioactive molecules and genetic alterability. Although it was believed that type III PKSs exist exclusively in plants and bacteria, recent fungal genome sequencing projects and biochemical studies revealed the presence of type III PKSs in filamentous fungi, which provides a new chance to study fungal secondary metabolism and synthesize "unnatural" natural products. Type III PKSs have been used for the biosynthesis of novel molecules through precursor-directed and structure-based mutagenesis approaches.
authors.affiliation: Department of Applied Chemistry and Biological Engineering, College of Chemical Engineering, Northeast Dianli University, Jilin, Jilin Province, People's Republic of China.
authors.forename: Dayu
authors.initials: D
authors.lastname: Yu
authors.forename: Fuchao
authors.initials: F
authors.lastname: Xu
authors.forename: Jia
authors.initials: J
authors.lastname: Zeng
authors.forename: Jixun
authors.initials: J
authors.lastname: Zhan
mesh_terms: D001419:Bacteria / Q000201:enzymology / Q000235:genetics; D001426:Bacterial Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism; D001688:Biological Products / Q000737:chemistry / Q000378:metabolism*; D005656:Fungal Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism; D005658:Fungi / Q000201:enzymology / Q000235:genetics; D060847:Metabolic Engineering; D016296:Mutagenesis; D010940:Plant Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism; D010944:Plants / Q000201:enzymology / Q000235:genetics; D048630:Polyketide Synthases / Q000145:classification* / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D001688:Biological Products; D005656:Fungal Proteins; D010940:Plant Proteins; D048630:Polyketide Synthases