Wild-type and mutant alleles of the Aspergillus nidulans developmental regulator gene brlA: correlation of variant sites with protein function

Abstract

The DNA sequences of two wild-type and eleven mutant alleles of the developmental regulator gene brlA from Aspergillus nidulans, which encodes a zinc-finger protein, were characterized. Variant sites were located on rescued plasmids or PCR products based either on their meiotic map position or the use of denaturing gradient gel electrophoresis. Mutations in three null mutants, one of which is partially suppressible, encode premature stop codons. Two environmentally sensitive mutants were characterised by substitution of leucines required for stabilisation of alpha-helices in each of the two putative zinc-finger domains. A third zinc-finger substitution is predicted to disrupt recognition of a guanine residue in the DNA target. The mutations in four other leaky mutants map C-terminal to the zinc fingers; one minimally leaky mutant has a premature stop codon, which results in the removal of the last 38 residues of the protein product.

A Pcl-Like Cyclin of Aspergillus nidulans Is Transcriptionally Activated by Developmental Regulators and Is Involved in Sporulation

“…Second, deletion of the pclA gene leads to a severe reduction of conidiospore production but not to any other morphological changes of the conidiophore. The isolation of a leaky brlA allele is in agreement with a recent analysis of different null and leaky brlA mutations, where it was shown that the majority of leaky mutations lie in the 3Ј half of the gene, possibly in the region that carries the presumptive DNA binding domain (18). Hypomorphic brlA alleles permit more extensive development than null mutants, which only form conidiophore stalks but no more differentiated cells, demonstrating the complexity and the central importance of brlA in the regulation of sporulation.…”

Genetic and Physical Mapping of Two Centromere-Proximal Regions of Chromosome IV in Aspergillus nidulans

“…Our estimates for the parameter P agree well with earlier observations (Clutterbuck, 1992;Griffith et al, 1999). The small discrepancy (8.1 kb/cM against 5 kb/cM) may be due to a lower frequency of recombination in this particular segment of chromosome IV (which probably contains some pericentric DNA) as compared to the genome as a whole.…”

InAspergillus nidulansthe SuppressorssuaAandsuaCCode for Release Factors eRF1 and eRF3 andsuaDCodes for a Glutamine tRNA

“…suaC maps on linkage group VII, shows linkage to choA (data not shown), and has a similar broad spectrum of suppression to the suaA suppressor strains. suaC109 suppresses the UAG mutations in alX4 , alcR125 , and areA600 , as well as the UAA mutation in areA601 (Sealy-Lewis 1987) and brlA17 , but not the UAA mutations in brlA19 or brlA4 or the UAG mutation in brlA24 (Griffith et al 1999). suaC109 strains were crossed with UGA containing pal − strains palC143 , palF15 , palB7 , and palB513 (mutations that affect pH regulation) in an attempt to establish whether suaC109 could suppress UGA mutations, but the crosses were infertile.…”