Project description:The recent discovery of a velvet complex containing several regulators of secondary metabolism in the model fungus Aspergillus nidulans raises the question whether similar type complexes direct fungal development in genera other than Aspergillus. Penicillium chrysogenum is the industrial producer of the antibiotic penicillin, whose biosynthetic regulation is barely understood. Here we provide a functional analysis of two major homologues of the velvet complex in P. chrysogenum, that we have named PcvelA and PclaeA. Data from array analysis using a ?PcvelA deletion strain indicate a significant role of PcvelA on the expression of biosynthesis and developmental genes, including PclaeA. Northern hybridization and HPLC quantifications of penicillin titres clearly show that both PcvelA and PclaeA play a major role in penicillin biosynthesis. Both regulators are further involved in different and distinct developmental processes. While PcvelA deletion leads to light independent conidial formation, dichotomous branching of hyphae and pellet formation in shaking cultures, a ?PclaeA strain shows a severe impairment in conidiophore formation in both the light and dark. Bimolecular fluorescence complementation assays finally provide evidence for a velvet-like complex in Penicillium chrysogenum, with structurally conserved components that have distinct developmental roles, illustrating the functional plasticity of these regulators within filamentous ascomycetes. Transcriptomes of PcvelA- and PclaeA- deletion mutants were compared with expression data from recipient strain deltaPcku70 and reference strain P2niaD18 as a control
Project description:The recent discovery of a velvet complex containing several regulators of secondary metabolism in the model fungus Aspergillus nidulans raises the question whether similar type complexes direct fungal development in genera other than Aspergillus. Penicillium chrysogenum is the industrial producer of the antibiotic penicillin, whose biosynthetic regulation is barely understood. Here we provide a functional analysis of two major homologues of the velvet complex in P. chrysogenum, that we have named PcvelA and PclaeA. Data from array analysis using a ΔPcvelA deletion strain indicate a significant role of PcvelA on the expression of biosynthesis and developmental genes, including PclaeA. Northern hybridization and HPLC quantifications of penicillin titres clearly show that both PcvelA and PclaeA play a major role in penicillin biosynthesis. Both regulators are further involved in different and distinct developmental processes. While PcvelA deletion leads to light independent conidial formation, dichotomous branching of hyphae and pellet formation in shaking cultures, a ΔPclaeA strain shows a severe impairment in conidiophore formation in both the light and dark. Bimolecular fluorescence complementation assays finally provide evidence for a velvet-like complex in Penicillium chrysogenum, with structurally conserved components that have distinct developmental roles, illustrating the functional plasticity of these regulators within filamentous ascomycetes.
Project description:Penicillium chrysogenum was successfully engineered to produce a novel carbamoylated cephalosporin that can be used as a synthon for semi-synthetic cephalosporins. To this end, structural genes for Acremonium chrysogenum expandase/hydroxylase and Streptomyces clavuligerus carbamoyltransferase were expressed in a penicillinG high-producing strain of P. chrysogenum. Growth of the engineered strain in the presence of the side-chain precursor adipic acid resulted in production of adipoyl-7-amino-3-carbamoyloxymethyl-3-cephem-4-carboxylic acid (ad7-ACCCA) and of several adipoylated pathway intermediates. A combinatorial chemostat-based transcriptome study, in which the ad7-ACCCA- producing strain and a strain lacking key genes in β-lactam synthesis were grown in the presence and absence of adipic acid, enabled the dissection of transcriptional responses to adipic acid per se and to ad7-ACCCA production. In chemostat cultures of both strains, adipic acid served as an additional carbon source. Transcriptome analysis supported an earlier proposal, based on 13C-labelling studies, that adipic acid catabolism in P. chrysogenum occurs via β-oxidation and enabled the identification of putative genes for enzymes involved in mitochondrial and peroxisomal β-oxidation pathways. Several of the genes that showed a specifically altered transcript level in ad7-ACCCA-producing cultures were previously implicated in oxidative stress responses. As strain improvement programmes lead to increased specific productivity and yields, a deeper understanding of these stress responses is likely to be important to also achieve high ad7-ACCCA titers with engineered strains of P. chrysogenum.