Message - 7th IAL Symposium

The 7 th International Association for Lichenology Symposium 2012
(1B-P5) Submission ID: IAL0322-00001
A SURVEY AND ANALYSIS OF POLYKETIDE SYNTHASE GENES IN
PELTIGERA MEMBRANACEA MYCOBIONTS
Gagunashvili A. 1 , Andresson O. 1
1 Department of Life and Environmental Sciences, University of Iceland, Reykjavik, Iceland
Polyketides are a group of secondary metabolites produced by a wide range of living organisms. These
compounds exhibit remarkable diversity both in terms of their structure and their 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. Genome sequencing projects
on filamentous fungi have revealed an unexpectedly large number of PKS gene clusters in their genomes,
very often exceeding the number of known polyketide metabolites for a certain species. Thus, the products
of many sequenced PKS clusters remain to be elucidated. Here we present a survey and analysis of PKS
genes in a recently sequenced metagenome of the foliose lichen Peltigera membranacea, along with analysis of
corresponding gene clusters, methylation and expression (RNA-Seq) data. We have identified 11 full-length
PKS genes, coding for 2 non-reducing and 9 reducing PKS enzymes, including one PKS-NRPS with a truncated
NRPS module. Not all deduced splice sites have been confirmed with RNA-Seq data, and some introns appear
not to be spliced at all or exhibit alternative splicing.
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