Isolation and characterisation of the acetyl-CoA carboxylase gene from Aspergillus nidulans

Abstract

The putative gene encoding acetyl-CoA carboxylase, accA, has been isolated from Aspergillus nidulans. This single-copy gene has an open reading frame (ORF) of 6864 bp and contains two small introns near the 5'-end. A short ORF upstream of the ATG start codon has been identified in this gene by RT-PCR. Based on sequence homology to acetyl-CoA carboxylases from other organisms, putative biotin-, ATP-, HCO3-- and acetyl-CoA- binding sites have been assigned. Northern data and ACC enzyme-activity measurements from A. nidulans suggested that expression of accA was higher in media containing nitrate than ammonia as a sole nitrogen source. Deletion of accA in A. nidulans was unsuccessful. The failure of A. nidulans to grow in the presence of the ACC-specific inhibitor, soraphen A, supplemented with C16-18 fatty acids suggested that ACC is an essential enzyme.

Effect of nitrogen sources on the activities of lipogenic enzymes in oleaginous fungus Cunninghamella echinulata.

“…Supernatant was centrifuged again at 20,000ϫg for 30 min at ϩ4°C. The determination of individual enzyme activities was performed in the resultant supernatant fraction by the following methods: ACL (EC 4.1.3.8) (Srere, 1962), ACC (EC 6.4.1.2) (Morrice et al, 1998), ME (malate dehydrogenase decarboxylating; EC 1.1.1.40) (Ochoa, 1955), GPD (EC 1.1.1.49) (Kuby and Noltmann, 1966), PGD (EC 1.1.1.44) (Pontremoli and Grazi, 1966), and NADP-ICD (EC 1.1.1.42) (Kornberg, 1955). At least three measurements for each enzyme activity were carried out to assess reproducibility.…”

ATP-Citrate Lyase Is Required for Production of Cytosolic Acetyl Coenzyme A and Development in Aspergillus nidulans

“…In A. nidulans the gene accA, encoding acetyl-CoA carboxylase, which is necessary for the conversion of acetyl-CoA to malonyl-CoA (and therefore for fatty acid biosynthesis and chain elongation), has been isolated, but attempts to delete the gene were unsuccessful (30). Furthermore, the ACC-specific inhibitor soraphen A inhibited growth even in the presence of added fatty acids, indicating that this enzyme is essential (30). Acetyl-CoA is a substrate for acetoacetyl-CoA thiolase (EC 2.3.1.9) and also for the subsequent synthesis of 3-hydroxy-3-methyl-glutaryl-CoA in the mevalonate-ergosterol biosynthetic pathway.…”

Relationship between Secondary Metabolism and Fungal Development

“…Feng and Leonard (42) also observed no sterigmatocystin production in ammonium-containing media. Other studies (65,82) indicate sterigmatocystin and aflatoxin production increases in ammonium-based media and decreases in nitratebased medium. Nitrogen source influences not only mycotoxin production but also the formation of developmental structures in Aspergillus spp.…”