title: The bZIP protein MeaB mediates virulence attributes in Aspergillus flavus.
abstract: LaeA is a fungal specific virulence factor of both plant and human pathogenic fungi. Transcriptional profiles of laeA mutants have been successfully exploited to identify regulatory mechanisms of secondary metabolism in fungi; here we use laeA mutants as tools to elucidate virulence attributes in Aspergillus flavus. Microarray expression profiles of ΔlaeA and over-expression laeA (OE::laeA) were compared to wild type A. flavus. Strikingly, several nitrogen metabolism genes are oppositely mis-regulated in the ΔlaeA and OE::laeA mutants. One of the nitrogen regulatory genes, the bZIP encoding meaB, is up-regulated in ΔlaeA. Significantly, over-expression of meaB (OE::meaB) phenocopies the decreased virulence attributes of a ΔlaeA phenotype including decreased colonization of host seed, reduced lipase activity and loss of aflatoxin B1 production in seed. However, a double knock-down of laeA and meaB (KD::laeA,meaB) demonstrated that KD::laeA,meaB closely resembled ΔlaeA rather than wild type or ΔmeaB in growth, aflatoxin biosynthesis and sclerotia production thus suggesting that meaB does not contribute to the ΔlaeA phenotype. MeaB and LaeA appear to be part of regulatory networks that allow them to have both shared and distinct roles in fungal biology.
authors.affiliation: Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.
authors.forename: Saori
authors.initials: S
authors.lastname: Amaike
authors.forename: Katharyn J
authors.initials: KJ
authors.lastname: Affeldt
authors.forename: Wen-Bing
authors.initials: WB
authors.lastname: Yin
authors.forename: Stephen
authors.initials: S
authors.lastname: Franke
authors.forename: Anjali
authors.initials: A
authors.lastname: Choithani
authors.forename: Nancy P
authors.initials: NP
authors.lastname: Keller
mesh_terms: D000348:Aflatoxins / Q000096:biosynthesis; D001231:Aspergillus flavus / Q000235:genetics* / Q000378:metabolism* / Q000472:pathogenicity; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism*; D017353:Gene Deletion; D055785:Gene Knockdown Techniques; D009154:Mutation; D009566:Nitrates / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D014774:Virulence / Q000235:genetics
chemical_list: D000348:Aflatoxins; D050976:Basic-Leucine Zipper Transcription Factors; D005656:Fungal Proteins; D009566:Nitrates; D009584:Nitrogen
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