title: An Aspergillus nidulans bZIP response pathway hardwired for defensive secondary metabolism operates through aflR.
abstract: The eukaryotic bZIP transcription factors are critical players in organismal response to environmental challenges. In fungi, the production of secondary metabolites (SMs) is hypothesized as one of the responses to environmental insults, e.g. attack by fungivorous insects, yet little data to support this hypothesis exists. Here we establish a mechanism of bZIP regulation of SMs through RsmA, a recently discovered YAP-like bZIP protein. RsmA greatly increases SM production by binding to two sites in the Aspergillus nidulans AflR promoter region, a C6 transcription factor known for activating production of the carcinogenic and anti-predation SM, sterigmatocystin. Deletion of aflR in an overexpression rsmA (OE:rsmA) background not only eliminates sterigmatocystin production but also significantly reduces asperthecin synthesis. Furthermore, the fungivore, Folsomia candida, exhibited a distinct preference for feeding on wild type rather than an OE:rsmA strain. RsmA may thus have a critical function in mediating direct chemical resistance against predation. Taken together, these results suggest RsmA represents a bZIP pathway hardwired for defensive SM production.
authors.affiliation: Departments of Medical Microbiology and Immunology Plant Pathology Genetics Bacteriology, University of Wisconsin-Madison, WI, USA.
authors.forename: Wen-Bing
authors.initials: WB
authors.lastname: Yin
authors.forename: Saori
authors.initials: S
authors.lastname: Amaike
authors.forename: Dana J
authors.initials: DJ
authors.lastname: Wohlbach
authors.forename: Audrey P
authors.initials: AP
authors.lastname: Gasch
authors.forename: Yi-Ming
authors.initials: YM
authors.lastname: Chiang
authors.forename: Clay C C
authors.initials: CC
authors.lastname: Wang
authors.forename: Jin Woo
authors.initials: JW
authors.lastname: Bok
authors.forename: Marko
authors.initials: M
authors.lastname: Rohlfs
authors.forename: Nancy P
authors.initials: NP
authors.lastname: Keller
mesh_terms: D000818:Animals; D001233:Aspergillus nidulans / Q000235:genetics / Q000378:metabolism*; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D007313:Insecta; D011401:Promoter Regions, Genetic; D013241:Sterigmatocystin / Q000096:biosynthesis*; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: C113837:AFLR protein, Aspergillus; D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D014157:Transcription Factors; D013241:Sterigmatocystin