The Aspergillus nidulans metE gene is regulated by a second system independent from sulphur metabolite repression

Mutations in the Aspergillus nidulans metE gene lead to requirement for O-a cetylhomoserine. The gene was cloned by complementation of the metE31 mutat ion. The coding sequence was found to be interrupted by two introns of 66 a nd 50 bp, respectively. metE codes for a peptide of 489 amino acids which b elongs to the family of homoserine O-acetyltransferases and a well-defined superfamily of alpha/beta hydrolases. Transcription of the metE gene is str ongly up-regulated by a severe limitation of methionine, but nut of cystein e. This gene is the first sulphur metabolism gene described in A. nidulans which is not regulated by the sulphur metabolite repression system in which cysteine acts as the low-molecular-weight effector. (C) 2001 Elsevier Scie nce B.V. All rights reserved.