Structure and regulation of cysD, the homocysteine synthase gene of Aspergillus nidulans

Curr Genet. 1998 Feb;33(2):136-44. doi: 10.1007/s002940050319.

Abstract

The A. nidulans cysD gene encoding homocysteine synthase (O-acetyl-L-homoserine sulphydrylase) has been isolated by functional complementation of a cysD11 mutation. The gene contains five short introns and codes for a protein of 437 amino acids. The protein shows homology with bacterial and yeast O-acetyl- and O-succinyl-homoserine sulphydrylases, particularly from Schizosaccharomyces pombe, Saccharomyces cerevisiae and Kluyveromyces lactis. The cysD cDNA is able to complement a S. cerevisiae mutation impairing homocysteine synthase. Synthesis of the cysD mRNA is down-regulated by a high concentration of methionine in growth medium without sulphate and up-regulated under sulphur limitation. A comparison of cysD genomic and cDNA copies, derived from different A. nidulans strains, revealed a marked DNA-sequence polymorphism manifested mostly by silent point mutations. There was, however, much less polymorphism in the protein sequence.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Aspergillus nidulans / enzymology*
  • Aspergillus nidulans / genetics
  • Base Sequence
  • Carbon-Oxygen Lyases / chemistry
  • Carbon-Oxygen Lyases / genetics*
  • Cloning, Molecular
  • Cysteine Synthase
  • DNA, Complementary / isolation & purification
  • DNA, Fungal / chemistry
  • Molecular Sequence Data
  • Multienzyme Complexes*
  • Saccharomyces cerevisiae Proteins*
  • Sequence Alignment

Substances

  • DNA, Complementary
  • DNA, Fungal
  • Multienzyme Complexes
  • Saccharomyces cerevisiae Proteins
  • Cysteine Synthase
  • MET17 protein, S cerevisiae
  • O-acetylhomoserine (thiol)-lyase
  • Carbon-Oxygen Lyases

Associated data

  • GENBANK/U19394