Abstract Detail

Secondary Metabolites

Wee, Josephine [1], Linz, John [2].

Transcriptional Regulation and Subcellular Localization of Aflatoxin Biosynthesis.

Fungi are known for their remarkable ability to synthesize secondary metabolites that have pharmaceutical (penicillin) and/or toxic (aflatoxin) properties.  Fungi are eukaryotic organisms that thrive under diverse environmental conditions.  The biosynthetic pathways for many known secondary metabolites have been extensively studied.  However, how multiple environmental signals are integrated to trigger gene regulatory networks that control expression of secondary metabolite clusters remains unclear. The filamentous fungus, Aspergillus parasiticus grows on a variety of susceptible food crops and produces aflatoxin, a carcinogen that is both a health and economic threat.  The transcriptome of A. parasicitus contains approximately 14,000 transcripts including those from the aflatoxin cluster and from approximately 42 other secondary metabolite clusters. Previous work addressed the molecular mechanisms that trigger the biosynthesis of aflatoxin and identified two cellular targets, AtfB and Vps34. Canonically known as a stress response transcription factor and a Class III endosomal lipid enzyme respectively, we demonstrated that AtfB and Vps34 regulatory networks coordinate expression of aflatoxin genes and localization of aflatoxin enzymes to aflatoxisomes. Our results also suggest that AtfB and Vps34 represent central nodes that co-regulate secondary metabolism, stress response, and conidiospore development via the same regulatory networks.  We then use examples from ongoing work to illustrate how cellular response to a specific environmental signal such as nutrient (sugar), light, and oxidative stress help coordinate function of the AtfB and Vps34 networks.  Finally, we ask if AtfB and Vps34 could help regulate the other 42 secondary metabolite clusters in A. parasiticus.

1 - Michigan State University, Food Science and Human Nutrition and Center for Integrative Toxicology, 469 Wilson Road, Room 200 G.M. Trout Food Science Building, East Lansing, Michigan, 48824-1224, USA
2 - Michigan State University, Food Science and Human Nutrition, East Lansing, Michigan, 48824-1224, USA

Keywords:
Aflatoxin
secondary metabolite
Stress response
Endosome trafficking
Regulatory Networks.

Presentation Type: Symposium or Colloquium Presentation
Session: SY3
Location: Room 104 AB/Kellogg Hotel and Conference Center
Date: Monday, June 9th, 2014
Time: 5:00 PM
Number: SY3005
Abstract ID:153
Candidate for Awards:None