Identification and analysis of clonable extragenic suppressors of the nimXcdc2F223L mutation of Aspergillus nidulans.

Sarah Lea McQuire, Melanie D. Schrader, Brett W. Carter, Dana L. Roe, Chad D. Young, Sean P. Grace, Gene A. Lang, and Suzanne E. Wahrle.


The nimXcdc2 protein kinase of Aspergillus nidulans regulates progression of nuclear division during G1>, S, and G2> phases of the cell cycle. To identify genes which encode proteins that interact with nimXcdc2, we have generated a collection of strains with mutations that suppress the temperature-sensitive nimXcdc2F223L mutation. The suppressor strains were screened for the presence of an additional phenotype (cold- or drug-sensitivity) that could be used in cloning. Of 1500 suppressors isolated, 37 contained additional phenotypes. 14 suppressor strains with additional phenotypes have been crossed with a wild-type strain to determine if the suppressor mutations were intragenic or extragenic. This yielded two strains with extragenic suppressor mutations that cosegregate with the additional phenotype. These strains were designated MDS250 and CY17. Both suppressor mutations have been shown to be recessive by diploid analysis, and phenotypic analysis indicates that both mutations stop the cell cycle during interphase. The growth phenotype of CY17 contains aberrant nuclear and cytoplasmic morphologies that indicate deregulation of tyrosine phosphorylation of nimXcdc2. We are currently performing analyses to determine at which point during interphase the nuclear division cycle is halted in these strains. In addition, both suppressor mutations are being mapped to chromosome to facilitate cloning and the remaining 23 suppressor strains are being analyzed genetically.

abstract No: 

Fungal Genet. Newsl. 46 (Supl):

Full conference title: 

Fungal Genetics Conference 20th
    • Fungal Genetics Conference 20th (1999)