abstract:Isolation of an Aspergillus developmental regulator

Tue Aug 30 11:01:46 EST 1994

Overexpression of flbA, an early regulator of Aspergillus asexual 
sporulation, leads to activation of brlA and premature initiation of 
Bee Na Lee and Thomas H. Adams
Department of Biology, Texas A&M University, College Station, TX  77843
Telephone:		409-845-1468, FAX:			409-845-2891, E-mail		Tom at bio.tamu.edu
Molecular Microbiology (1994).  In Press


	Aspergillus nidulans reproduces asexually by forming thousands of 
mitotically derived spores atop highly specialized multicellular organs 
termed conidiophores.  We have identified a gene called flbA (for fluffy low 
brlA expression) that is required for initiation of A. nidulans conidiophore 
development.  flbA mutants also form abnormal colonies that have a distinct 
fluffy phenotype characterized by tightly interwoven aerial hyphae that 
autolyse as the colony matures.  The requirement for flbA in conidiophore 
development precedes activation of brlA, a primary regulator of conidiophore 
development.  The wild type flbA  gene was isolated and found to encode a 
3.0 kb mRNA that is expressed throughout the A. nidulans asexual life cycle.  
Overexpression of flbA using an inducible promoter resulted in misscheduled 
expression of brlA in vegetative cells and caused hyphal tips to 
differentiate into spore producing structures.  Sequence analysis of a 
nearly full length flbA cDNA clone showed that flbA is predicted to encode a 
717 amino acid polypeptide with 30% identity to the Saccharomyces cerevisiae 
SST2 protein.  SST2 is required by yeast cells for resuming growth following 
prolonged exposure to yeast mating pheromone and for mating partner 
discrimination.  We propose that flbA plays a related role in a signaling 
pathway for Aspergillus conidiophore development. 

Tom Adams
Department of Biology
Texas A&M University
College Station, TX  77843
Tom at bio.tamu.edu

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