Submitted to: American Chemical Society Annual Meeting Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: July 18, 2002
Publication Date: August 15, 2002
Citation: GIBSON, D.M. USING MOLECULAR PROBES IN THE SEARCH FOR NOVEL SOURCES OF SECONDARY METABOLITES FROM INSECT PATHOGENIC FUNGI. AMERICAN CHEMICAL SOCIETYS ANNUAL MEETING SYMPOSIUM PROCEEDINGS. 2002. Technical Abstract: Fungi in the ecological niches associated with insects, soil, litter, or plants interact with many other organisms, and these interactions are likely to be moderated by small molecules having novel chemistries. Since little is known of the chemistry profiles of many insect associated fungi, a molecular approach was developed to initially screen fungi for their potential to produce polyketides, based on detection of conserved regions of the genes encoding polyketide synthase (PKS). We used a degenerate PCR primer approach to probe genomic DNA for the highly conserved ketosynthase (KS) domain of PKS in a genetically diverse group of insect and nematode associated fungi for which the capacity to produce polyketides is largely undescribed. Out of a starting group of 157 fungal isolates representing 73 genera, 92 isolates contained a putative KS domain. Based on sequence analysis of the putative fragments, 72% showed a high similarity to known KS domains. Sequence analysis of the fragments indicated several groupings of fungal KS domains distinct from known PKS genes. The study showed that a molecular screening approach could detect the presence of PKS genes across a diverse group of fungi from which the chemical potential for PK synthesis is largely unknown and that PKS genes are widespread and diverse among insect and nematode associated fungi. Based on the putative relatedness of gene fragment groupings, we are currently determining whether these novel PKS genes and their polyketide products are functionally dedicated to the specialized activities of these organisms.