Funding Source

National Science Foundation, National Institutes of Health

Grant Number

MCB-9874646, NSF MCB-0236393, SO6GM08008


Department of Biology

Document Type


Publication Date



In contrast to most primary metabolism genes, the genes involved in secondary metabolism and certain nutrient utilization pathways are clustered in fungi. Recently a nuclear protein, LaeA, was found to be required for the transcription of several secondary metabolite gene clusters in Aspergillus nidulans. Here we show that LaeA regulation does not extend to nutrient utilization or the spoC1 sporulation clusters. One of the secondary metabolite clusters regulated by LaeA contains the positive regulatory (i.e. aflR) and biosynthetic genes required for biosynthesis of sterigmatocystin (ST), a carcinogenic toxin. Analysis of ST gene cluster expression indicates LaeA regulation of the cluster is location specific as transcription of genes bordering the ST cluster are unaffected in a ΔlaeA mutant and placement of a primary metabolic gene, argB, in the ST cluster resulted in argB silencing in the ΔlaeA background. ST cluster gene expression was remediated when an additional copy of aflR was placed outside of the cluster but not when placed in the cluster. Site-specific mutation of an s-adenosyl methionine (AdoMet) binding site in LaeA generated a ΔlaeA phenotype suggesting the protein to be a methyltransferase.


DOI: 10.1111/j.1365-2958.2006.05330.x

PubMed ID: 16968230

Acknowledgements This research was funded by NSF Grant MCB-9874646 and NSF MCB-0236393 to N.P.K. and NIH (MBRS) Grant No. SO6GM08008 to S.P.K