Chemistry Weekly Seminar - John Sorensen, University of Manitoba
John Sorensen, Department of Chemistry, University of Manitoba, will present a seminar at 1:30 pm in ARTS 146.
Title
Linking genes to molecules in lichen fungi using metabolite profiling and heterologous expression
Abstract
Lichen fungi, symbiotic associations between fungal (mycobiont) and algal partners (photobiont), are characterized by their ubiquity, occupying diverse ecological and geological niches. Lichen fungi have demonstrated an ability to produce a variety of novel bioactive natural products such as usnic acid. However, slow growth rates and challenges with laboratory culturing have limited the pace of discovery. However, despite these challenges there has been a resurgence of interest in the biosynthesis of natural products in lichen fungi. In large part this is due to the availability of inexpensive genome sequencing and the development of highly sensitive mass spectroscopic methods for the characterization of metabolite profiles. Metabolite profiling using LC-MS techniques have revealed the presence of previously undetected metabolites in lichen fungi. Additionally, research carried out both in our laboratory, and others around the world, has revealed that lichen fungi harbour a number of silent or ‘cryptic’ biosynthetic gene clusters. These gene clusters appear intact and likely to code for the production of a secondary metabolite, but their gene sequence does not appear to be similar to any known pathway. This suggest that the full biosynthetic potential of lichen fungi has yet to be revealed.
We have two complementary approaches to the discovery of new natural products in lichen fungi. One major focus in on examining the metabolite profile with LC-MS/MS techniques and using resources such as GNPS to identify metabolites and link this information to biosynthetic gene clusters in the genome. This presentation will describe our recent results on linking squamatic acid to a gene cluster. Complementary to this approach is the heterologous expression of cryptic gene clusters in a heterologous host to assign conclusive function. Recent work with 6-hydroxymelinin gene cluster will be described. Some of our more recent results have been focusing on the function of accessory genes in the biosynthetic clusters. Our characterization of a fully functional decarboxylase gene will be described.
Date: Friday, November 25, 2022
Time: 1:30 pm
Place: Arts 146