J Fungi (Basel)
November 2022
In L-rhamnose is catabolised to pyruvate and L-lactaldehyde, and the latter ultimately to L-lactate, via the non-phosphorylated pathway (LRA) encoded by the genes -, and that encodes a broad substrate range aldehyde dehydrogenase (ALDH) that also functions in ethanol utilisation. LRA pathway expression requires both the pathway-specific transcriptional activator RhaR ( is expressed constitutively) and the presence of L-rhamnose. The deletion of severely impairs growth when L-rhamnose is the sole source of carbon and in addition it abolishes the induction of genes that respond to L-rhamnose/RhaR, indicating that an intermediate of the LRA pathway is the physiological inducer likely required to activate RhaR.
View Article and Find Full Text PDFProtoplast transformation for the introduction of recombinant DNA into is technically demanding and dependant on the availability and batch variability of commercial enzyme preparations. Given the success of -mediated transformation (ATMT) in diverse pathogenic fungi, we have adapted this method to facilitate transformation of . Using suitably engineered binary vectors, gene-targeted ATMT of non-homologous end-joining (NHEJ) mutant conidia has been carried out for the first time by complementation of a nutritional requirement (uridine/uracil auxotrophy).
View Article and Find Full Text PDFL-rhamnose (6-deoxy-mannose) occurs in nature mainly as a component of certain plant structural polysaccharides and bioactive metabolites but has also been found in some microorganisms and animals. The release of L-rhamnose from these substrates is catalysed by extracellular enzymes including α-L-rhamnosidases, the production of which is induced in its presence. The free sugar enters cells via specific uptake systems where it can be metabolized.
View Article and Find Full Text PDFIndependent systems of high and low affinity effect glucose uptake in the filamentous fungus Aspergillus nidulans. Low-affinity uptake is known to be mediated by the product of the mstE gene. In the current work two genes, mstA and mstC, have been identified that encode high-affinity glucose transporter proteins.
View Article and Find Full Text PDFIn a previous study, alcS, a gene of the Aspergillus nidulans alc cluster, was shown to encode a protein that belongs to the GPR1/FUN34/YaaH membrane protein family. BLAST screening of the A. nidulans genome data identified additional genes encoding hypothetical proteins that could belong to this family.
View Article and Find Full Text PDFThe ability to perform multiple gene deletions is an important tool for conducting functional genomics. We report the development of a sequential gene deletion protocol for the filamentous fungus Aspergillus nidulans using the Cre/loxP recombinase system of bacteriophage P1. A recyclable genetic marker has been constructed by incorporating loxP direct repeats either side of the Neurospora crassa pyr-4 gene (encodes orotidine 5'-monophosphate decarboxylase) which is able to complement the A.
View Article and Find Full Text PDFThe mstE gene encoding a low affinity glucose transporter active during the germination of Aspergillus nidulans conidia on glucose medium has been identified. mstE expression also occurs in hyphae, is induced in the presence of other repressing carbon sources besides glucose, and is dependent on the function of the transcriptional repressor CreA. The expression of MstE and its subcellular distribution have been studied using a MstE-sGFP fusion protein.
View Article and Find Full Text PDFA sugar-transporter-encoding gene, mstA, which is a member of the major facilitator superfamily, has been cloned from a genomic DNA library of the filamentous fungus Aspergillus niger. To enable the functional characterization of MSTA, a full-length cDNA was expressed in a Saccharomyces cerevisiae strain deficient in hexose uptake. Uptake experiments using 14C-labelled monosaccharides demonstrated that although able to transport D-fructose ( K(m), 4.
View Article and Find Full Text PDFMicrobiology (Reading)
August 2003
D-Glucose uptake in germinating wild-type Aspergillus nidulans conidia is an energy-requiring process mediated by at least two transport systems of differing affinities for glucose: a low-affinity system (K(m) approximately 1.4 mM) and a high-affinity system (K(m) approximately 16 micro M). The low-affinity system is inducible by glucose; the high-affinity system is subject to glucose repression effected by the carbon catabolite repressor CreA and is absent in sorA3 mutant conidia, which exhibit resistance to L-sorbose toxicity.
View Article and Find Full Text PDFThe shoot apical meristem (SAM), initially formed during embryogenesis, gives rise to the aboveground portion of the maize (Zea mays) plant. The shootless phenotype (sml) described here is caused by disruption of SAM formation due to the synergistic interaction of mutations at two genetic loci. Seedlings must be homozygous for both sml (shootmeristemless), and the unlinked dgr (distorted growth) loci for a SAM-less phenotype to occur.
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