Molecular characterization, function and regulation of ammonium transporters (Amt) and ammonium‐metabolizing enzymes (GS, NADP‐GDH) in the ectomycorrhizal fungus Hebeloma cylindrosporum

@article{Javelle2003MolecularCF,
  title={Molecular characterization, function and regulation of ammonium transporters (Amt) and ammonium‐metabolizing enzymes (GS, NADP‐GDH) in the ectomycorrhizal fungus Hebeloma cylindrosporum},
  author={A. Javelle and M. Morel and B. Rodr{\'i}guez-Pastrana and B. Botton and B. Andr{\'e} and A. Marini and A. Brun and M. Chalot},
  journal={Molecular Microbiology},
  year={2003},
  volume={47}
}
External hyphae, which play a key role in nitrogen nutrition of trees, are considered as the absorbing structures of the ectomycorrhizal symbiosis. Here, we have cloned and characterized Hebeloma cylindrosporum AMT1, GLNA and GDHA genes, which encode a third ammonium transporter, a glutamine synthetase and an NADP‐dependent glutamate dehydrogenase respectively. Amt1 can fully restore the pseudohyphal growth defect of a Saccharomyces cerevisiae mep2 mutant, and this is the first evidence that a… Expand
Ectomycorrhiza-mediated repression of the high-affinity ammonium importer gene AmAMT2 in Amanita muscaria
TLDR
Together these data suggest that (1) AmAMT2 expression is regulated by the endogenous nitrogen content of hyphae and (2) fungal hyphAE in ectomycorrhizas are well supported with nitrogen even when the extraradical mycelium is nitrogen limited. Expand
Amt2 Permease Is Required To Induce Ammonium-Responsive Invasive Growth and Mating in Cryptococcus neoformans
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It is proposed that Amt2 may be a new fungal ammonium sensor and an element of the signaling cascades that govern the mating of C. neoformans in response to environmental nutritional cues. Expand
GintAMT2, a new member of the ammonium transporter family in the arbuscular mycorrhizal fungus Glomus intraradices.
TLDR
The isolation and characterization of a new G. intraradicesNH(4)(+) transporter gene (GintAMT2) is reported and it is shown that GintAMMT2 encodes a functional NH(4](+) transporter. Expand
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Analysis of internal and external ammonia accumulation by ΔmepB strains in mycelia and germinated spores showed rapid uptake and accumulation, and reduced secretion of ammonia in the mutant versus wild-type (WT) strains, suggesting MEPB expression's contribution to pathogenicity. Expand
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The functional and expression properties, described in the present study, delineate TbNrt2 as a versatile transporter that may be especially suited to cope with the fluctuating (and often low) mineral nitrogen concentrations found in most natural, especially forest, soils. Expand
GintAMT1 encodes a functional high-affinity ammonium transporter that is expressed in the extraradical mycelium of Glomus intraradices.
TLDR
Data suggest that GintAMT1 is involved in NH(4)(+) uptake by the extraradical mycelia from the surrounding media when it is present at micromolar concentrations, as revealed by [(14)C]methylammonium uptake experiments carried out in yeast. Expand
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Regulation of the Nitrogen Transfer Pathway in the Arbuscular Mycorrhizal Symbiosis: Gene Characterization and the Coordination of Expression with Nitrogen Flux1[W][OA]
TLDR
The gene expression pattern and profiling of metabolites involved in the N pathway support the idea that the rapid uptake, translocation, and transfer of N by the fungus successively trigger metabolic gene expression responses in the extraradical mycelium, intraradicals, and host plant. Expand
NADP-dependent glutamate dehydrogenase: a dispensable function in ectomycorrhizal fungi.
TLDR
It is hypothesized that the lack of a functional NADP-GDH could be an evolutive adaptation in relation to the ecological niche of ECM fungi, rather than a transitional regulation in response to changes in N contents of the extracellular medium. Expand
Isolation and characterization from pathogenic fungi of genes encoding ammonium permeases and their roles in dimorphism
TLDR
A model of how ammonium transporters play a role in regulating dimorphic growth in fungi is presented and the importance of a putative site for phosphorylation by protein kinase A was investigated in both Mep2p and Ump2p via site‐directed mutagenesis of the respective genes. Expand
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