Dataset Information

Protein kinase C (PkcA) of Aspergillus nidulans is involved in penicillin production.

ABSTRACT: The biosynthesis of the beta-lactam antibiotic penicillin in the filamentous fungus Aspergillus nidulans is catalyzed by three enzymes that are encoded by the acvA, ipnA, and aatA genes. A variety of cis-acting DNA elements and regulatory factors form a complex regulatory network controlling these beta-lactam biosynthesis genes. Regulators involved include the CCAAT-binding complex AnCF and AnBH1. AnBH1 acts as a repressor of the penicillin biosynthesis gene aatA. Until now, however, little information has been available on the signal transduction cascades leading to the transcription factors. Here we show that inhibition of protein kinase C (Pkc) activity in A. nidulans led to cytoplasmic localization of an AnBH1-enhanced green fluorescent protein (EGFP) fusion protein. Computer analysis of the genome and screening of an A. nidulans gene library revealed that the fungus possesses two putative Pkc-encoding genes, which we designated pkcA and pkcB. Only PkcA showed all the characteristic features of fungal Pkc's. Production of pkcA antisense RNA in A. nidulans led to reduced growth and conidiation in Aspergillus minimal medium, while in fermentation medium it led to enhanced expression of an aatAp-lacZ gene fusion, reduced pencillin production, and predominantly cytoplasmic localization of AnBH1. These data agree with the finding that inhibition of Pkc activity prevented nuclear localization of AnBH1-EGFP. As a result, repression of aatA expression was relieved. The involvement of Pkc in penicillin biosynthesis is also interesting in light of the fact that in the yeast Saccharomyces cerevisiae, Pkc plays a major role in maintaining cell integrity.

SUBMITTER: Herrmann M

PROVIDER: S-EPMC1449056 | biostudies-literature | 2006 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Protein kinase C (PkcA) of Aspergillus nidulans is involved in penicillin production.

Herrmann Martina M Spröte Petra P Brakhage Axel A AA

Applied and environmental microbiology 20060401 4

The biosynthesis of the beta-lactam antibiotic penicillin in the filamentous fungus Aspergillus nidulans is catalyzed by three enzymes that are encoded by the acvA, ipnA, and aatA genes. A variety of cis-acting DNA elements and regulatory factors form a complex regulatory network controlling these beta-lactam biosynthesis genes. Regulators involved include the CCAAT-binding complex AnCF and AnBH1. AnBH1 acts as a repressor of the penicillin biosynthesis gene aatA. Until now, however, little info ...[more]

PMID: 16598003

Similar Datasets

Project description:BACKGROUND:The production of bioethanol from lignocellulosic feedstocks is dependent on lignocellulosic biomass degradation by hydrolytic enzymes. The main component of lignocellulose is cellulose and different types of organisms are able to secrete cellulases. The filamentous fungus Aspergillus nidulans serves as a model organism to study cellulase production and the available tools allow exploring more in depth the mechanisms governing cellulase production and carbon catabolite repression. RESULTS:In A. nidulans, microarray data identified the cAMP-dependent protein kinase A (PkaA) as being involved in the transcriptional modulation and the production of lignocellulolytic enzymes in the presence of cellulose. Deletion of pkaA resulted in increased hydrolytic enzyme secretion, but reduced growth in the presence of lignocellulosic components and various other carbon sources. Furthermore, genes involved in fungal development were increased in the ?pkaA strain, probably leading to the increased hyphal branching as was observed in this strain. This would allow the secretion of higher amounts of proteins. In addition, the expression of SynA, encoding a V-SNARE synaptobrevin protein involved in secretion, was increased in the ?pkaA mutant. Deletion of pkaA also resulted in the reduced nuclear localization of the carbon catabolite repressor CreA in the presence of glucose and in partial de-repression when grown on cellulose. PkaA is involved in the glucose signaling pathway as the absence of this protein resulted in reduced glucose uptake and lower hexokinase/glucokinase activity, directing the cell to starvation conditions. Genome-wide transcriptomics showed that the expression of genes encoding proteins involved in fatty acid metabolism, mitochondrial function and in the use of cell storages was increased. CONCLUSIONS:This study shows that PkaA is involved in hydrolytic enzyme production in A. nidulans. It appears that this protein kinase blocks the glucose pathway, hence forcing the cell to change to starvation conditions, increasing hydrolytic enzyme secretion and inducing the usage of cellular storages. This work uncovered new regulatory avenues governing the tight interplay between the metabolic states of the cell, which are important for the production of hydrolytic enzymes targeting lignocellulosic biomass. Deletion of pkaA resulted in a strain with increased hydrolytic enzyme secretion and reduced biomass formation.

Project description:BACKGROUND:Despite recent advances in the understanding of lignocellulolytic enzyme regulation, less is known about how different carbon sources are sensed and the signaling cascades that result in the adaptation of cellular metabolism and hydrolase secretion. Therefore, the role played by non-essential protein kinases (NPK) and phosphatases (NPP) in the sensing of carbon and/or energetic status was investigated in the model filamentous fungus Aspergillus nidulans. RESULTS:Eleven NPKs and seven NPPs were identified as being involved in cellulase, and in some cases also hemicellulase, production in A. nidulans. The regulation of CreA-mediated carbon catabolite repression (CCR) in the parental strain was determined by fluorescence microscopy, utilising a CreA::GFP fusion protein. The sensing of phosphorylated glucose, via the RAS signalling pathway induced CreA repression, while carbon starvation resulted in derepression. Growth on cellulose represented carbon starvation and derepressing conditions. The involvement of the identified NPKs in the regulation of cellulose-induced responses and CreA derepression was assessed by genome-wide transcriptomics (GEO accession 47810). CreA::GFP localisation and the restoration of endocellulase activity via the introduction of the ?creA mutation, was assessed in the NPK-deficient backgrounds. The absence of either the schA or snfA kinase dramatically reduced cellulose-induced transcriptional responses, including the expression of hydrolytic enzymes and transporters. The mechanism by which these two NPKs controlled gene transcription was identified, as the NPK-deficient mutants were not able to unlock CreA-mediated carbon catabolite repression under derepressing conditions, such as carbon starvation or growth on cellulose. CONCLUSIONS:Collectively, this study identified multiple kinases and phosphatases involved in the sensing of carbon and/or energetic status, while demonstrating the overlapping, synergistic roles of schA and snfA in the regulation of CreA derepression and hydrolytic enzyme production in A. nidulans. The importance of a carbon starvation-induced signal for CreA derepression, permitting transcriptional activator binding, appeared paramount for hydrolase secretion.

Dataset Information

Protein kinase C (PkcA) of Aspergillus nidulans is involved in penicillin production.

Publications

Protein kinase C (PkcA) of Aspergillus nidulans is involved in penicillin production.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets