A Sec7 domain gene has a role in Aspergillus nidulans morphogenesis.

Lifeng Chen, Yi Yang, Susan Kaminskyj.

Author address: 

Dept Biology, Univ Saskatchewan, Saskatoon, SK S7N 5E2, Canada


A Sec7 domain containing sequence was isolated as an extragenic suppressor of the Aspergillus nidulans hypB5 temperature sensitive morphogenesis defect. A hypB5 mutant strain was transformed with the pRG3-AMA1 library. A complementing plasmid was rescued, and a 5 kb KpnI fragment containing the complementing region was cloned into pBluescript as pYY2. The restrictive phenotype of hypB5 mutant strains is restricted colonial growth, and slow-growing cells with aberrant branching. The pYY2-transformed strains have wildtype colonies at 42C. At 42C these hyphae have shorter basal cells with more nuclei than the wildtype parent strain A28. An intact Sec7domain is required for wildtype colony growth: pYY2 with Tn1000-disruptions in, but not adjacent to, the Sec7 domain failed to rescue the hypB5 temperature sensitive defect. The pYY2 Sec7 domain is 81% identical to Saccharomyces cerevisiae SEC7. In A. nidulans it is located in the predicted protein An6709.2. Structural modeling shows good theoretical agreement with the Sec7 domain of human ARNO (ADP Ribosylation Nucleotide Opener). The Sec7 domain is 10% of the predicted length of An6709.2; the remainder of the predicted gene lacks homologies to characterized sequences. In other Sec7 genes, the conserved F-G loop is critical for function. We are using site-directed mutagenesis to examine effects of single residue replacements on hyphal morphogenesis

abstract No: 


Full conference title: 

23rd Fungal Genetics Conference
    • Fungal Genetics Conference 23rd (2002)