The Loss-of-Function Mutation Leads to Enhanced α-L-Rhamnosidase Production by .

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.

-Mediated Transformation of NHEJ Mutant Conidia: An Efficient Tool for Targeted Gene Recombination Using Selectable Nutritional Markers.

Protoplast 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).

Catabolism of L-rhamnose in A. nidulans proceeds via the non-phosphorylated pathway and is glucose repressed by a CreA-independent mechanism.

L-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.

High-affinity glucose transport in Aspergillus nidulans is mediated by the products of two related but differentially expressed genes.

Independent 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.

AcpA, a member of the GPR1/FUN34/YaaH membrane protein family, is essential for acetate permease activity in the hyphal fungus Aspergillus nidulans.

In 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.

Consecutive gene deletions in Aspergillus nidulans: application of the Cre/loxP system.

The 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.

Identification of the mstE gene encoding a glucose-inducible, low affinity glucose transporter in Aspergillus nidulans.

The 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.

Aspergillus niger mstA encodes a high-affinity sugar/H+ symporter which is regulated in response to extracellular pH.

A 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.

Glucose uptake in germinating Aspergillus nidulans conidia: involvement of the creA and sorA genes.

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.

Mutations in two independent genes lead to suppression of the shoot apical meristem in maize.

The 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.