ORCID Profile
0000-0002-3046-8240
Current Organisation
University of Kansas
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Publisher: American Chemical Society (ACS)
Date: 29-02-2012
DOI: 10.1021/JA209809T
Publisher: Springer Science and Business Media LLC
Date: 09-2009
Publisher: American Society for Microbiology
Date: 15-12-2008
DOI: 10.1128/AEM.01743-08
Abstract: The sequencing of Aspergillus genomes has revealed that the products of a large number of secondary metabolism pathways have not yet been identified. This is probably because many secondary metabolite gene clusters are not expressed under normal laboratory culture conditions. It is, therefore, important to discover conditions or regulatory factors that can induce the expression of these genes. We report that the deletion of sumO , the gene that encodes the small ubiquitin-like protein SUMO in A. nidulans , caused a dramatic increase in the production of the secondary metabolite asperthecin and a decrease in the synthesis of austinol/dehydroaustinol and sterigmatocystin. The overproduction of asperthecin in the sumO deletion mutant has allowed us, through a series of targeted deletions, to identify the genes required for asperthecin synthesis. The asperthecin biosynthesis genes are clustered and include genes encoding an iterative type I polyketide synthase, a hydrolase, and a monooxygenase. The identification of these genes allows us to propose a biosynthetic pathway for asperthecin.
Publisher: Elsevier BV
Date: 06-2008
Publisher: Oxford University Press (OUP)
Date: 03-2006
DOI: 10.1534/GENETICS.105.052563
Abstract: Aspergillus nidulans is an important experimental organism, and it is a model organism for the genus Aspergillus that includes serious pathogens as well as commercially important organisms. Gene targeting by homologous recombination during transformation is possible in A. nidulans, but the frequency of correct gene targeting is variable and often low. We have identified the A. nidulans homolog (nkuA) of the human KU70 gene that is essential for nonhomologous end joining of DNA in double-strand break repair. Deletion of nkuA (nkuAΔ) greatly reduces the frequency of nonhomologous integration of transforming DNA fragments, leading to dramatically improved gene targeting. We have also developed heterologous markers that are selectable in A. nidulans but do not direct integration at any site in the A. nidulans genome. In combination, nkuAΔ and the heterologous selectable markers make up a very efficient gene-targeting system. In experiments involving scores of genes, 90% or more of the transformants carried a single insertion of the transforming DNA at the correct site. The system works with linear and circular transforming molecules and it works for tagging genes with fluorescent moieties, replacing genes, and replacing promoters. This system is efficient enough to make genomewide gene-targeting projects feasible.
Publisher: Microbiology Society
Date: 12-2010
Abstract: Gene-silencing mechanisms are being shown to be associated with an increasing number of fungal developmental processes. Telomere position effect (TPE) is a eukaryotic phenomenon resulting in gene repression in areas immediately adjacent to telomere caps. Here, TPE is shown to regulate expression of transgenes on the left arm of chromosome III and the right arm of chromosome VI in Aspergillus nidulans . Phenotypes found to be associated with transgene repression included reduction in radial growth and the absence of sexual spores however, these pleiotropic phenotypes were remedied when cultures were grown on media with appropriate supplementation. Simple radial growth and ascosporogenesis assays provided insights into the mechanism of TPE, including a means to determine its extent. These experiments revealed that the KU70 homologue (NkuA) and the heterochromatin-associated proteins HepA, ClrD and HdaA were partially required for transgene silencing. This study indicates that TPE extends at least 30 kb on chromosome III, suggesting that this phenomenon may be important for gene regulation in subtelomeric regions of A. nidulans.
Publisher: American Chemical Society (ACS)
Date: 06-02-2009
DOI: 10.1021/JA8088185
Publisher: Elsevier BV
Date: 10-2011
Publisher: Springer Science and Business Media LLC
Date: 12-2006
Abstract: We describe a rapid method for the production of fusion PCR products that can be used, generally without band purification, to transform Aspergillus nidulans. This technique can be used to replace genes tag genes with fluorescent moeties or epitope tags or replace endogenous promoters with regulatable promoters, by introducing an appropriate selective cassette (e.g., fluorescent protein + selectable marker). The relevant genomic fragments and cassette are first lified separately by PCR using primers that produce overlapping ends. A second PCR using 'nested' primers fuses the fragments into a single molecule with all sequences in the desired order. This procedure allows a cassette to be lified once, frozen and used subsequently in many fusion PCRs. Transformation of nonhomologous recombination deficient (nkuADelta) strains of A. nidulans with fusion PCR products results in high frequencies of accurate gene targeting. Fusion PCR takes less than 2 d. Protoplast formation and transformation takes less than 1 d.
Publisher: American Society for Microbiology
Date: 04-2010
DOI: 10.1128/AEM.02187-09
Abstract: Deletion of cclA , a component of the COMPASS complex of Aspergillus nidulans , results in the production of monodictyphenone and emodin derivatives. Through a set of targeted deletions in a cclA deletion strain, we have identified the genes required for monodictyphenone and emodin analog biosynthesis. Identification of an intermediate, endocrocin, from an mdpH Δ strain suggests that mdpH might encode a decarboxylase. Furthermore, by replacing the promoter of mdpA (a putative aflJ homolog) and mdpE (a putative aflR homolog) with the inducible alcA promoter, we have confirmed that MdpA functions as a coactivator. We propose a biosynthetic pathway for monodictyphenone and emodin derivatives based on bioinformatic analysis and characterization of biosynthetic intermediates.
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3SC02226A
Abstract: Secondary metabolites are important for the pathogenesis of the fungus Aspergillus fumigatus which causes lethal Aspergillosis. Expressing groups of A. fumigatus genes in the fungus Aspergillus nidulans reveals new A. fumigatus secondary metabolites.
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/B904541D
Publisher: Springer Science and Business Media LLC
Date: 17-05-2009
DOI: 10.1038/NCHEMBIO.177
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Berl Oakley.