title: Negative regulation and developmental competence in Aspergillus.
abstract: Asexual development (conidiation) in the filamentous fungus Aspergillus nidulans is governed by orchestrated gene expression. The three key negative regulators of conidiation SfgA, VosA, and NsdD act at different control point in the developmental genetic cascade. Here, we have revealed that NsdD is a key repressor affecting the quantity of asexual spores in Aspergillus. Moreover, nullifying both nsdD and vosA results in abundant formation of the development specific structure conidiophores even at 12 h of liquid culture, and near constitutive activation of conidiation, indicating that acquisition of developmental competence involves the removal of negative regulation exerted by both NsdD and VosA. NsdD's role in repressing conidiation is conserved in other aspergilli, as deleting nsdD causes enhanced and precocious activation of conidiation in Aspergillus fumigatus or Aspergillus flavus. In vivo NsdD-DNA interaction analyses identify three NsdD binding regions in the promoter of the essential activator of conidiation brlA, indicating a direct repressive role of NsdD in conidiation. Importantly, loss of flbC or flbD encoding upstream activators of brlA in the absence of nsdD results in delayed activation of brlA, suggesting distinct positive roles of FlbC and FlbD in conidiation. A genetic model depicting regulation of conidiation in A. nidulans is presented.
authors.affiliation: Department of Bacteriology, The University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.|Department of Biological Sciences and Center for Biotechnology Research, Institute for Ubiquitous Information Technology and Applications (UBITA), Konkuk University, Seoul 143-701, Republic of Korea.
authors.forename: Mi-Kyung
authors.initials: MK
authors.lastname: Lee
authors.affiliation: Department of Bacteriology, The University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Nak-Jung
authors.initials: NJ
authors.lastname: Kwon
authors.affiliation: Department of Biological Sciences and Center for Biotechnology Research, Institute for Ubiquitous Information Technology and Applications (UBITA), Konkuk University, Seoul 143-701, Republic of Korea.
authors.forename: Im-Soon
authors.initials: IS
authors.lastname: Lee
authors.affiliation: Department of Bioscience and Biotechnology and Center for Biotechnology Research, Institute for Ubiquitous Information Technology and Applications (UBITA), Konkuk University, Seoul 143-701, Republic of Korea.
authors.forename: Seunho
authors.initials: S
authors.lastname: Jung
authors.affiliation: Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Dae-Jeon, Republic of Korea.
authors.forename: Sun-Chang
authors.initials: SC
authors.lastname: Kim
authors.affiliation: Department of Bacteriology, The University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Jae-Hyuk
authors.initials: JH
authors.lastname: Yu
mesh_terms: D000595:Amino Acid Sequence; D001232:Aspergillus fumigatus / Q000235:genetics / Q000502:physiology; D001233:Aspergillus nidulans / Q000235:genetics* / Q000502:physiology; D005656:Fungal Proteins / Q000235:genetics*; D017353:Gene Deletion; D018507:Gene Expression Regulation, Developmental; D015966:Gene Expression Regulation, Fungal; D008957:Models, Genetic; D012100:Reproduction, Asexual / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013172:Spores, Fungal / Q000235:genetics* / Q000254:growth & development
chemical_list: D005656:Fungal Proteins