The specific interaction of chromate with the dual sulfate permease systems of Neurospora crassa

摘要: Abstract Chromate inhibits growth and eventually causes cell death in Neurospora crassa . Mutants resistant to chromate show stage-specific deficiencies sulfate transport parallel losses uptake. The toxicity of is completely dependent upon the sulfur source provided for growth. mutant strains are chromate-resistant when methionine present but very sensitive analog inorganic serves as sole source. a competitive inhibitor K i inhibition (3 × 10 −5 m ) nearly identical entry. energy dependent, inhibited by sulfate, repressed occurs on methionine-supplemented media, clearly via permease systems. seems include two aspects: (1) specific perhaps early assimilatory steps, (2) general lethality due entry strong oxidizing activity chromate. mutants largely exclude thus protected from generalized toxic effect. Tungstate molybdate similar, far weaker, systems at higher concentrations cause all strains.