Isocitrate lyase is essential for growth of microorganisms on 2C compounds and fatty acids, and is located in the glyoxysomes in Aspergillus nidulans. The structure of isocitrate lyase from A. nidulans has been solved at 2.8 A using X-ray crystallography. The secondary structure of this tetrameric enzyme is arranged into two main domains, one of which forms a peripheral head domain to the enzyme molecule, and corresponds to an internal sequence of approximately 100 amino acids which is not found in prokaryotic ICLs. To understand the structure/function relationships of this enzyme including the molecular factors which control the differential targetting of the enzyme to glyoxysome in eukaryote and cytoplasm in prokaryote, a null mutant A. nidulans has been constructed by transformational deletion of the isocitrate lyase (acuD) gene for use as an expression host for acuD mutants generated in vitro. Mutations made to date include deletion of the internal additional amino acid sequence, and the disordered C-terminal region which may be involved in protein targetting. Mutated acuD was inserted into the null mutant by cotransformation. The results of the structure analysis of this enzyme and of the programme of mutagenesis designed to test proposals on the enzyme mechanism and intracellular location will be presented.
Fungal Genet. Newsl. 46 (Supl):
Full conference title:
Fungal Genetics Conference 20th
- Fungal Genetics Conference 20th (1999)