A homologue of the Aspergillus velvet gene regulates both cephalosporin C biosynthesis and hyphal fragmentation in Acremonium chrysogenum.
The Aspergillus nidulans velvet (veA) gene encodes a global regulator of gene expression controlling sexual development as well as secondary metabolism. We have identified the veA homologue AcveA from Acremonium chrysogenum, the major producer of the beta-lactam antibiotic cephalosporin C. Two different disruption strains as well as the corresponding complements were generated as a prelude to detailed functional analysis. Northern hybridization and quantitative real-time PCR clearly indicate that the nucleus-localized AcVEA polypeptide controls the transcriptional expression of six cephalosporin C biosynthesis genes. The most drastic reduction in expression is seen for cefEF, encoding the deacetoxycephalosporine/deacetylcephalosporine synthetase. After 120 h of growth, the cefEF transcript level is below 15% in both disruption strains compared to the wild type. These transcriptional expression data are consistent with results from a comparative and time-dependent high-performance liquid chromatography analysis of cephalosporin C production. Compared to the recipient, both disruption strains have a cephalosporin C titer that is reduced by 80%. In addition to its role in cephalosporin C biosynthesis, AcveA is involved in the developmentally dependent hyphal fragmentation. In both disruption strains, hyphal fragmentation is already observed after 48 h of growth, whereas in the recipient strain, arthrospores are not even detected before 96 h of growth. Finally, the two mutant strains show hyperbranching of hyphal tips on osmotically nonstabilized media. Our findings will be significant for biotechnical processes that require a defined stage of cellular differentiation for optimal production of secondary metabolites.
Dreyer
Jacqueline
J
Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universität, Universitätsstr. 150, D-44780 Bochum, Germany.
Eichhorn
Heiko
H
Friedlin
Ernst
E
Kürnsteiner
Hubert
H
Kück
Ulrich
U
D000164:Acremonium / Q000166:cytology / Q000235:genetics* / Q000502:physiology*; D001233:Aspergillus nidulans / Q000235:genetics; D015152:Blotting, Northern; D002511:Cephalosporins / Q000096:biosynthesis*; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D017353:Gene Deletion; D015870:Gene Expression; D015966:Gene Expression Regulation, Fungal; D005809:Genes, Regulator; D005816:Genetic Complementation Test; D025301:Hyphae / Q000502:physiology*; D008969:Molecular Sequence Data; D009024:Morphogenesis; D010105:Oxygenases / Q000096:biosynthesis; D012329:RNA, Bacterial / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013172:Spores, Fungal
D002511:Cephalosporins; D004271:DNA, Fungal; D012329:RNA, Bacterial; D012333:RNA, Messenger; C025163:cephalosporin C; D010105:Oxygenases; C045288:deacetoxycephalosporin C hydroxylase