Open AccessSuppressor Mutagenesis Identifies a Velvet Complex Remediator of Aspergillus nidulans Secondary Metabolism
Author(s) -
Mona I. Shaaban,
Jin Woo Bok,
Carrie Lauer,
Nancy P. Keller
Publication year - 2010
Publication title -
eukaryotic cell
Language(s) - English
Resource type - Journals
eISSN - 1535-9778
pISSN - 1535-9786
DOI - 10.1128/ec.00189-10
Subject(s) - aspergillus nidulans , biology , secondary metabolism , velvet , transcription factor , sterigmatocystin , leucine zipper , gene , mutagenesis , genetics , microbiology and biotechnology , mutation , mutant , biosynthesis , mycotoxin , botany , chemistry , organic chemistry
Fungal secondary metabolites (SM) are bioactive compounds that are important in fungal ecology and, moreover, both harmful and useful in human endeavors (e.g., as toxins and pharmaceuticals). Recently a nuclear heterocomplex termed the Velvet complex, characterized in the model ascomyceteAspergillus nidulans , was found to be critical for SM production. Deletion of two members of the Velvet complex,laeA andveA , results in near loss of SM and defective sexual spore production inA. nidulans and other species. Using a multicopy-suppressor genetics approach, we have isolated anAspergillus nidulans gene namedrsm A (remediation of secondary metabolism) based upon its ability to remediate secondary metabolism in ΔlaeA and ΔveA backgrounds. Overexpression ofrsmA (OE::rsmA ) restores production of sterigmatocystin (ST) (a carcinogenic SM) via transcriptional activation of ST biosynthetic genes. However, defects in sexual reproduction in either ΔlaeA or ΔveA strains cannot be overcome by OE::rsmA . An intact Velvet complex coupled with an OE::rsmA allele increases SM many fold over the wild-type level, but loss ofrsmA does not decrease SM. RsmA encodes a putative bZIP basic leucine zipper-type transcription factor.