Please use this identifier to cite or link to this item: http://hdl.handle.net/1946/22418
Polyketides are a group of secondary metabolites produced by a wide range of living organisms – bacteria, fungi, plants and animals. These compounds exhibit remarkable structural diversity and possess an extremely broad spectrum of biological activity. Polyketides are of great commercial interest for drug discovery since many of these compounds have desirable pharmaceutical properties and they are a source of novel antibiotics, anti-tumor and anti-cancer agents, as well as cholesterol-lowering drugs.
The biosynthesis of polyketides is catalyzed by large multifunctional enzymes called polyketide synthases (PKSs) that assemble core polyketide molecules from simple starter carboxylic acid precursors and several malonyl-CoA units in a manner similar to fatty acid synthesis.
Although polyketide synthesis is widespread in filamentous fungi and lichen mycobionts, relatively few PKS genes have been isolated from filamentous fungi and no PKS gene from lichens can be found in the GenBank database except the one from the lichen Solorina crocea recently submitted.
Although lichens produce various pharmaceutically relevant polyketides and have been appreciated in traditional medicines, their value has largely been ignored by the modern pharmaceutical industry because slow growth and difficulties in establishing pure cultures do not allow their routine use in most conventional screening processes. Recently, molecular genetic techniques using PCR, genomic library construction and heterologous expression in surrogate hosts have provided an alternative approach to begin accessing, exploring and harnessing the diversity of polyketide biosynthetic pathways in lichens.
The aim of this work was the surrogate expression of a PKS gene from the lichen Solorina crocea in the filamentous fungus Aspergillus oryzae, analysis of the product(s) of its expression and determination of the gene structure: exon–intron boundaries, 5′- and 3′-prime ends, the native promoter region and the domain organization of the deduced protein sequence.