Enzymatic lesions in methionine mutants of Aspergillus nidulans: role and regulation of an alternative pathway for cysteine and methionine synthesis.

摘要: Abstract In Aspergillus nidulans the pathway involving cystathionine formation is main one for homocysteine synthesis. Mutants lacking gamma-synthase or beta-cystathionase are auxotrophs suppressible by: (i) mutations in of cysteine synthesis (cysA1, cysB1, and cysC1), (ii) causing stimulation catabolism (su101), (iii) a presumed regulatory gene (suAmeth). A relative shortage first group suppressors causes derepression synthase, enzyme involved alternative similar observed suAmeth strain. Homocysteine synthesized by this serves as precursor methionine mutant with altered synthase prototroph, indicating that not essential fungus.