Purification and Characterization of the NAD-Dependent Glutamate Dehydrogenase in the Ectomycorrhizal FungusLaccaria bicolor(Maire) Orton

Garnier, Alix; Berredjem, A.; Botton, Bernard

doi:10.1006/fgbi.1997.1004

Cited by 15 publications

(7 citation statements)

References 36 publications

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“…Concerning the assimilation component, it has been shown that glutamate increased ammonium assimilation in the ectomycorrhizal fungus L. laccata , glutamine synthetase (GS) being strongly activated [39]. The increased ammonium assimilation could partly explain the enhanced ammonium transport by glutamate in P. involutus .…”

Section: Resultsmentioning

confidence: 99%

Ammonium and methylamine transport by the ectomycorrhizal fungus Paxillus involutus and ectomycorrhizas

Javelle¹,

Chalot²,

Söderström

et al. 1999

FEMS Microbiology Ecology

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Using [(14)C]methylamine as an analogue of ammonium, the kinetics and the energetics of NH(4)(+) transport were studied in the ectomycorrhizal fungus, Paxillus involutus (Batsch) Fr. The apparent half-saturation constant (K(m)) and the maximum uptake rate (V(max)) for the carrier-mediated transport derived from the Eadie-Hofstee transformation were 180 µM and 380 nmol (mg dry wt)(-1) min(-1,) respectively. Both pH dependence and inhibition by protonophores indicate that methylamine transport in P. involutus was dependent on the electrochemical H(+) gradient. Both long-term and short-term uptake experiments were consistent with regulation of ammonium/methylamine transport processes by the presence of an organic nitrogen source. Analysis of methylamine uptake by different P. involutus isolates revealed no obvious trend in the uptake capacities in relation to N deposition at the collection site. Kinetic parameters were determined in P. involutus/Betula pendula (Roth.) axenic association and in detached mycorrhizal roots isolated from forest sites. Enhanced methylamine uptake in the presence of the fungal symbiont was demonstrated. Homogeneous V(max) values were found for axenic and detached mycorrhizas, whereas K(m) values showed greater variations.

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Section: Resultsmentioning

confidence: 99%

Ammonium and methylamine transport by the ectomycorrhizal fungus Paxillus involutus and ectomycorrhizas

Javelle¹,

Chalot²,

Söderström

et al. 1999

FEMS Microbiology Ecology

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“…The oxidative deamination of amino acids also seems to be an important route in the degradation and assimilation of amino acid skeletons since at least three different dehydrogenase transcripts were represented by four ESTs. These enzymes play a key role in nitrogen metabolism in many organisms and free ammonia is released as a product of catalysis (Garnier et al, 1997). Ammonia alters ambient pH in fungal cultures and regulates the expression of virulence genes in Met.…”

Section: Function Of Expressed Con Coronatus Genesmentioning

confidence: 99%

EST analysis of genes expressed by the zygomycete pathogen Conidiobolus coronatus during growth on insect cuticle

Freimoser

Screen

et al. 2003

Microbiology

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Conidiobolus coronatus (Zygomycota) is a facultative saprobe that is a pathogen of many insect species. Almost 2000 expressed sequence tag (EST) cDNA clones were sequenced to analyse gene expression during growth on insect cuticle. Sixty percent of the ESTs that could be clustered into functional groups (E⩽10−5) had their best blast hits among fungal sequences. These included chitinases and multiple subtilisins, trypsin, metalloprotease and aspartyl protease activities with the potential to degrade host tissues and disable anti-microbial peptides. Otherwise, compared to the ascomycete entomopathogen Metarhizium anisopliae, Con. coronatus produced many fewer types of hydrolases (e.g. no phospholipases), antimicrobial agents, toxic secondary metabolites and no ESTs with putative roles in the generation of antibiotics. Instead, Con. coronatus produced a much higher proportion of ESTs encoding ribosomal proteins and enzymes of intermediate metabolism that facilitate its rapid growth. These results are consistent with Con. coronatus having adapted a modification of the saprophytic ruderal-selected strategy, using rapid growth to overwhelm the host and exploit the cadaver before competitors overrun it. This strategy does not preclude specialization to pathogenicity, as Con. coronatus produces the greatest complexity of proteases on insect cuticle, indicating an ability to respond to conditions in the cuticle.

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“…With the exception of Mn 2+ , which did not affect the amination reaction but had a slightly stimulatory effect on the reverse reaction (25% at 1 mM), divalent metal cations (Zn 2+ , Ca 2+ , Mg 2+ ) slightly inhibited both GDH activities. All these results are comparable with those reported for other fungi such as L. bicolor (Garnier et al ., 1997), D. discoideum (Pamula & Wheldrake, 1991) and A. bisporus (Baars et al ., 1995). Chelating agents, such as 1,10‐phenanthroline or EDTA, determined a 20% inhibition of GDH activities.…”

Section: Resultsmentioning

confidence: 99%

“…This evidence suggested similar conformations for these enzymes (Blumenthal et al ., 1975) and a common evolutionary origin. Other GDHs such as NAD‐dependent GDH purified from Saccaromyces cerevisae (Uno et al ., 1984), N. crassa (Veronese et al ., 1974), Agaricus bisporus (Kersten et al ., 1999) and L. bicolor (Garnier et al ., 1997) have a tetrameric structure with subunits of 115–116 kDa.…”

Section: Introductionmentioning

confidence: 99%

Biochemical and molecular characterization of NADP‐glutamate dehydrogenase from the ectomycorrhizal fungus Tuber borchii

et al. 2002

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Summary• NADP-glutamate dehydrogenase (NADP-GDH) from Tuber borchii was purified and the corresponding gene was cloned in order to elucidate the physiological role of the enzyme in this ectomycorrhizal fungus.• NADP-GDH was purified using an anion-exchange column followed by affinity chromatography. The complete gene was cloned from a 30-d-old-mycelium cDNA library and characterized.• T. borchii NADP-GDH appears to be physically and kinetically similar to those from other fungi and the deduced amino acid sequence of the gdh gene showed a significant similarity to other fungal NADP-dependent GDHs. Biochemical and Northern blotting analyses carried out with mycelia grown on different nitrogen sources clearly showed that the regulation of T. borchii NADP-GDH in response to different nitrogen sources was markedly different from the responses of the NADPGDHs of other ascomycetes. Northern blotting analyses highlighted that the gdh gene was also expressed in the symbiotic phase.• The biochemical and molecular data suggest that the fungal NADP-GDH contributes to the primary nitrogen metabolism in the ectomycorrhizal tissues.

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Purification and Characterization of the NAD-Dependent Glutamate Dehydrogenase in the Ectomycorrhizal FungusLaccaria bicolor(Maire) Orton

Cited by 15 publications

References 36 publications

Ammonium and methylamine transport by the ectomycorrhizal fungus Paxillus involutus and ectomycorrhizas

Ammonium and methylamine transport by the ectomycorrhizal fungus Paxillus involutus and ectomycorrhizas

EST analysis of genes expressed by the zygomycete pathogen Conidiobolus coronatus during growth on insect cuticle

Biochemical and molecular characterization of NADP‐glutamate dehydrogenase from the ectomycorrhizal fungus Tuber borchii

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