Genetic control of amino acid transport in Aspergillus nidulans: evidence for polymeric amino acid permease

On a medium containing either acetate as the sole source of carbon or arginine as the sole source of nitrogen and the two amino acid analogs, p-fluorophenylalanine (FPA) and ethionine, eight FPA-resistant mutants were selected. Dominance tests in heterozygous diploids showed that 3 out of 8 are recessive, 1 semidominant, and 4 dominant to their wild-type alleles. Mutants were characterized by the nature of amino acid transport detected on the basis of amino acid utilization patterns. Six new loci identified after genetic analysis were located on two linkage groups: three each on linkage groups I and II. Recombinants between pairs of loci fpaD and fpaQ , and fpaK and fpaP , were found to be sensitive to FPA. The pattern of segregation of resistant markers and amino acid utilization were considered to characterize the specificity of transport mutants.