14 research outputs found
GABA transminase provides an alternative route of β-alanine synthesis in Aspergillus nidulans
Reduced expression of a distal gene of the prn gene cluster in deletion mutants of Aspergillus nidulans: Genetic evidence for a dicistronic messenger in an eukaryote
Do the tightly linked structural genes for nitrate and nitrite reductases in Aspergillus nidulans form an operon? Evidence from an insertional translocation which separates them
Extracellular arabinases in Aspergillus nidulans: the effect of different cre mutations on enzyme levels.
Identification, cloning and analysis of the Aspergillus niger gene pacC, a wide domain regulatory gene responsive to ambient pH.
Onset of carbon catabolite repression in Aspergillus nidulans
The role of hexose phosphorylating enzymes in the signaling of carbon catabolite repression was investigated in the filamentous fungus Aspergillus nidulans. A D-fructose non-utilizing, hexokinase-deficient (hxkA1, formerly designated frA1) strain was utilized to obtain new mutants lacking either glucokinase (glkA4) or both hexose kinases (hxkA1/glkA4). D-Glucose and D-fructose phosphorylation is completely abolished in the double mutant, which consequently cannot grow on either sugar. The glucokinase single mutant exhibits no nutritional deficiencies. Three repressible diagnostic systems, ethanol utilization (alcA and alcR genes), xylan degradation (xlnA), and acetate catabolism (facA), were analyzed in these hexose kinase mutants at the transcript level. Transcriptional repression by D-glucose is fully retained in the two single kinase mutants, whereas the hexokinase mutant is partially derepressed for D-fructose. Thus, hexokinase A and glucokinase A compensate each other for carbon catabolite repression by D-glucose in the single mutants. In contrast, both D-glucose and D-fructose repression are severely impaired for all three diagnostic systems in the double mutant. Unlike the situation in Saccharomyces cerevisiae, the hexose phosphorylating enzymes play parallel roles in glucose repression in A. nidulans
Identification, cloning and sequence of the Aspergillus niger areA wide domain regulatory gene controlling nitrogen utilisation.
Aspergillus nidulans CkiA is an essential casein kinase I required for delivery of amino acid transporters to the plasma membrane
Type I casein kinases are highly conserved among Eukaryotes. Of the two Aspergillus nidulans casein kinases I, CkiA is related to the δ/ε mammalian kinases and to Saccharomyces cerevisiæ Hrr25p. CkiA is essential. Three recessive ckiA mutations leading to single residue substitutions, and downregulation using a repressible promoter, result in partial loss-of-function, which leads to a pleiotropic defect in amino acid utilization and resistance to toxic amino acid analogues. These phenotypes correlate with miss-routing of the YAT plasma membrane transporters AgtA (glutamate) and PrnB (proline) to the vacuole under conditions that, in the wild type, result in their delivery to the plasma membrane. Miss-routing to the vacuole and subsequent transporter degradation results in a major deficiency in the uptake of the corresponding amino acids that underlies the inability of the mutant strains to catabolize them. Our findings may have important implications for understanding how CkiA, Hrr25p and other fungal orthologues regulate the directionality of transport at the ER-Golgi interface. © 2012 Blackwell Publishing Ltd