Submitted to: World Mycotoxin Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 15, 2010
Publication Date: February 15, 2011
Citation: Ehrlich, K., Mack, B.M., Cary, J.W., Bhatnagar, D., Kale, S.P. 2011. A hypothesis to explain how laeA specifically regulates certain secondary metabolite biosynthesis gene clusters. World Mycotoxin Journal. 4(1):53-58. Interpretive Summary: The toxic and carcinogenic mold toxin called aflatoxin is produced by Aspergillus flavus on corn, peanuts, and cottonseed. To produce this toxin a set of 29 genes are turned on almost simultaneously and make the necessary proteins. Previous studies from our laboratory identified the protein that turns on the genes. This protein is in a class of gene regulators that is found in all fungi and which may be necessary for turning genes on in other mycotoxin-producing gene clusters as well as in the aflatoxin cluster. Another protein, LaeA, has recently been identified as a key regulator of many secondary metabolite (including mycotoxins) gene clusters. We report in this paper a hypothesis that LaeA binds to AflR and to similar proteins to turn on the genes in many mycotoxin gene clusters. The proposal is supported by evidence from a sensitive binding assay.
Technical Abstract: Biosynthesis of mycotoxins involves transcriptional co-regulation of sets of clustered genes. We hypothesize that specific control of transcription of genes in these clusters by LaeA, a global regulator of secondary metabolite production and development in aspergilli and other filamentous fungi, results from its interaction with a Cys6Zn2 DNA-binding protein unique to the gene cluster.