Homolanthionine in fungi: accumulation in the methionine-requiring mutants of Aspergillus nidulans.

Homolanthionine, a higher homologue of cystathionine, was found to accumulate in the mutants of Aspergillus nidulan impaired in the synthesis of methionine from homocysteine. The additional introduction of mutation resulting in a block at cystathionine gamma-synthase but not at cystathionine beta-synthase abolishes accumulation of both homolanthionine and cystathionine. This suggests a possible participation of cystathionine gamma-synthase in homolanthionine synthesis.