Molecular characterization of the <i>Aspergillus nidulans treA</i> gene encoding an acid trehalase required for growth on trehalose

d’Enfert, Christophe; Fontaine, Thierry

doi:10.1046/j.1365-2958.1997.3131693.x

Cited by 106 publications

(100 citation statements)

References 47 publications

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“…The acid trehalase is extracellular in many other fungi (9,10,24,29) and in prokaryotes (6). Ath1p may be localized in vacuoles in S. cerevisiae (1,12,25).…”

Section: Trehalose [␣-D-glucopyranosyl-(1-1)-␣-d-glucopyranoside] Is mentioning

confidence: 99%

“…While Nwaka and coworkers (36) suggested that trehalose may reach the vacuole by simple endocytosis, Malluta et al (30) proposed that the disaccharide could be taken up by Agt1p. However, to be effective, this model implies the protection of internalized trehalose against neutral trehalase and the existence of two additional transporter activities by which trehalose enters the vacuole to be degraded by Ath1p and the subsequent exit of glucose from this compartment.The acid trehalase is extracellular in many other fungi (9,10,24,29) and in prokaryotes (6). Ath1p may be localized in vacuoles in S. cerevisiae (1,12,25).…”

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Two Distinct Pathways for Trehalose Assimilation in the Yeast Saccharomyces cerevisiae

Jules

Guillou

François

et al. 2004

Appl Environ Microbiol

100

141

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The yeast Saccharomyces cerevisiae can synthesize trehalose and also use this disaccharide as a carbon source for growth. However, the molecular mechanism by which extracellular trehalose can be transported to the vacuole and degraded by the acid trehalase Ath1p is not clear. By using an adaptation of the assay of invertase on whole cells with NaF, we showed that more than 90% of the activity of Ath1p is extracellular, splitting of the disaccharide into glucose. We also found that Agt1p-mediated trehalose transport and the hydrolysis of the disaccharide by the cytosolic neutral trehalase Nth1p are coupled and represent a second, independent pathway, although there are several constraints on this alternative route. First, the AGT1/MAL11 gene is controlled by the MAL system, and Agt1p was active in neither non-maltose-fermenting nor maltose-inducible strains. Second, Agt1p rapidly lost activity during growth on trehalose, by a mechanism similar to the sugar-induced inactivation of the maltose permease. Finally, both pathways are highly pH sensitive and effective growth on trehalose occurred only when the medium was buffered at around pH 5.0. The catabolism of trehalose was purely oxidative, and since levels of Ath1p limit the glucose flux in the cells, batch cultures on trehalose may provide a useful alternative to glucose-limited chemostat cultures for investigation of metabolic responses in yeast. Trehalose [␣-D-glucopyranosyl-(1-1)-␣-D-glucopyranoside] is a nonreducing disaccharide of glucose discovered in 1832 byWiggers in a mushroom crop and later in many other fungi, plants, and insects (13). In the yeast Saccharomyces cerevisiae, trehalose can accumulate up to 15% of the cell dry mass, depending on the growth conditions, the stage of the life cycle, or environmental stress (2, 27), and for this reason it has been considered a storage carbohydrate (15,27). Moreover, the ability of this disaccharide to protect proteins and biological membranes against adverse conditions suggests that it also plays a stress-protectant role in this yeast (49,50) and probably in other organisms that produce it (14).Intracellular levels of trehalose result from a well-controlled balance between enzymatic synthesis and degradation. In the yeast S. cerevisiae, the synthesis of trehalose is catalyzed by a UDP-glucose-dependent trehalose synthase (TPS) protein complex encoded by four genes. TPS1 and TPS2 encode trehalose-6-phosphate synthase and trehalose-6-phosphate phosphatase, respectively, while TPS3 and TSL1 code for two regulatory subunits of the TPS complex (for a review, see reference 15). Hydrolysis of trehalose into glucose can be carried out by at least two enzymes: a cytosolic or neutral trehalase encoded by NTH1 (26) and a vacuolar or acid trehalase (25, 28) encoded by ATH1 (12). The yeast genome also harbors the NTH2 gene, whose product is 77% identical to Nth1p, but until now, no trehalase activity has been associated with this protein (37). The neutral trehalase Nth1p is responsible for the intracellular mobilization ...

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“…The acid trehalase is extracellular in many other fungi (9,10,24,29) and in prokaryotes (6). Ath1p may be localized in vacuoles in S. cerevisiae (1,12,25).…”

Section: Trehalose [␣-D-glucopyranosyl-(1-1)-␣-d-glucopyranoside] Is mentioning

confidence: 99%

mentioning

confidence: 99%

Two Distinct Pathways for Trehalose Assimilation in the Yeast Saccharomyces cerevisiae

Jules

Guillou

François

et al. 2004

Appl Environ Microbiol

100

141

View full text Add to dashboard Cite

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“…It could therefore be suggested that this enzyme is active as a monomer. This is in contrast to other acid trehalases that are often active as dimers or multimers (Sumida et al, 1989 ;Zimmerman et al, 1990 ;Kadowaki et al, 1996 ;d'Enfert & Fontaine, 1997). Because the acid trehalase binds to concanavalin A, it is probably a glycosylated protein.…”

Section: mentioning

confidence: 99%

Identification and characterization of an extracellular acid trehalase from the ectomycorrhizal fungus Amanita muscaria

et al. 2000

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The non-reducing disaccharide trehalose is a major storage compound in most fungi. For a better understanding of carbon metabolism in the ectomycorrhizal-forming basidiomycete Amanita muscaria, trehalase activity was analysed from mycelium growing in liquid culture or on agar plates, and from mycorrhizas. Trehalase activity was found in both the culture medium and in mycelial extracts. The excreted trehalase was purified to apparent homogeneity by anion-exchange chromatography, gel filtration and preparative gel electrophoresis. The identified enzyme belongs to the group of acid trehalases. The apparent molecular mass of the native enzyme was estimated to be 165 kDa by gel filtration and 135 kDa by SDS-PAGE. Isoelectrofocusing indicated an isoelectric point (pI) of approx. 3.7, which is typical for acid trehalases. The enzyme is highly specific for its substrate trehalose, with an apparent K m of 0.38 mM. Validamycin and sucrose act as competitive inhibitors with K i values of 45 nM and 15 mM, respectively. The activity of acid trehalase excreted into the growth medium is independent of the carbon source (glucose or trehalose), revealing that the enzyme is not regulated by its substrate trehalose. Nevertheless, fungal hyphae grown in the absence of an external carbon source showed enhanced enzyme excretion. The biochemical characteristics of the trehalase activity measured in the mycelium are in the same range as those determined for the excreted enzyme. The enzyme is localized in the cell wall and its activity is strongly decreased in ectomycorrhizas.

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“…The concentrations of trehalose, mannitol, arabitol, and glycerol in the resting and germinating conidia were analyzed as described previously (23). Briefly, 1-week-old conidia (produced in 2% malt extract agar medium) were incubated in Sabouraud (SAB) liquid medium for 0 h, 3 h, and 6 h at 37°C in shake flasks at 300 rpm.…”

Section: Methodsmentioning

confidence: 99%

Pathway of Glycine Betaine Biosynthesis in Aspergillus fumigatus

et al. 2013

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Molecular characterization of the Aspergillus nidulans treA gene encoding an acid trehalase required for growth on trehalose

Cited by 106 publications

References 47 publications

Two Distinct Pathways for Trehalose Assimilation in the Yeast Saccharomyces cerevisiae

Two Distinct Pathways for Trehalose Assimilation in the Yeast Saccharomyces cerevisiae

Identification and characterization of an extracellular acid trehalase from the ectomycorrhizal fungus Amanita muscaria

Pathway of Glycine Betaine Biosynthesis in Aspergillus fumigatus

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