Methylamine and ammonia transport in Saccharomyces cerevisiae

Roon, Robert J.; Even, Harvey L.; Dunlop, P. C.; Larimore, F. L.

doi:10.1128/jb.122.2.502-509.1975

Cited by 124 publications

(43 citation statements)

References 14 publications

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“…3) indicates that methylamine can be used as an analogue to study ammonium uptake, as showm in previous studies [10^13 ,23]. Methylamine provides two potential ad- vantages over NH 4 : it is not metabolised by the cells [28], avoiding interference between metabolism and transport in uptake experiments, and uptake experiments can be carried out over short periods during which e¥ux is considered to be negligible.…”

Section: Uptake Of Methylamine Versus Uptake Of Ammoniummentioning

confidence: 89%

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

Javelle¹

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 WM and 380 nmol (mg dry wt) 31 min 31Y 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. ß acid FEMS Microbiology Ecology 30 (1999) 355^366

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Section: Uptake Of Methylamine Versus Uptake Of Ammoniummentioning

confidence: 89%

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

Javelle¹

1999

FEMS Microbiology Ecology

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“…Wild-type yeast cells with functional ammonium transporters are unable to grow in the presence of high concentrations of MA. However, yeast mutant strains that are impaired in ammonium (and MA) transport are able to grow on media containing 100 mM MA [27,28]. Thus, yeast mutant strain MLY131a/K was able to grow on 100 mM MA, but the same strain expressing AtAMT1 ;1 was not able to do so (Fig.…”

Section: Biochemical Analysis Of Ammonium Uptake By Atamt2mentioning

confidence: 99%

Characterization of Arabidopsis AtAMT2, a novel ammonium transporter in plants

et al. 2000

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We have cloned and characterized the first member of a novel family of ammonium transporters in plants: AtAMT2 from Arabidopsis thaliana. AtAMT2 is more closely related to bacterial ammonium transporters than to plant transporters of the AMT1 family. The protein was expressed and functionally characterized in yeast. AtAMT2 transported ammonium in an energy-dependent manner. In contrast to transporters of the AMT1 family, however, AtAMT2 did not transport the ammonium analogue, methylammonium. AtAMT2 was expressed more highly in shoots than roots and was subject to nitrogen regulation.z 2000 Federation of European Biochemical Societies.

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“…Ammonium was a strong competitive inhibitor of this activity, while other amino compounds and monovalent cations, such as Na+ and K+, were poor inhibitors. Since the Ki value for ammonium was much lower than the Km for methylamine, and since methylamine cannot serve as a carbon or nitrogen source for this organism, the natural substrate of this uptake activity should be ammonium rather than methylamine (Roon et al, 1975). In a further study, Dubois and Grenson (1979) showed that the uptake of methylamine/ammonium in S.cerevisiae is mediated by at least two functionally distinct systems.…”

Section: Introductionmentioning

confidence: 96%

“…The methyl analog of ammonium, methylamine, is commonly used in studies of ammonium transport systems (Hackette et al, 1970). Roon et al (1975) measured a [14C]methylamine uptake activity in S.cerevisiae which resulted in -1000fold accumulation. Ammonium was a strong competitive inhibitor of this activity, while other amino compounds and monovalent cations, such as Na+ and K+, were poor inhibitors.…”

Section: Introductionmentioning

confidence: 99%

Cloning and expression of the MEP1 gene encoding an ammonium transporter in Saccharomyces cerevisiae.

et al. 1994

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In Saccharomyces cerevisiae, the transport of ammonium across the plasma membrane for use as a nitrogen source is mediated by at least two functionally distinct transport systems whose respective encoding genes are called MEP1 and MEP2. Mutations in the MEP2 gene affect high affinity, low capacity ammonium transport while mutations in the MEP1 gene disrupt a lower affinity, higher capacity system. In this work, the MEP1 gene has been cloned and sequenced and its expression analyzed. The predicted amino acid sequence reveals a highly hydrophobic, 54 kDa protein with 10 or 11 putative membrane‐spanning regions. The predicted Mep1p protein shares high sequence similarity with several bacterial proteins of unknown function, notably the product of the nitrogen‐regulated nrgA gene of Bacillus subtilis, and with that of a partial cDNA sequence derived from Caenorhabditis elegans. The Mep1p and related proteins appear to define a new family of transmembrane proteins evolutionarily conserved in at least bacteria, fungi and animals. The MEP1 gene is most highly expressed when the cells are grown on low concentrations of ammonium or on ‘poor’ nitrogen sources like urea or proline. It is down‐regulated, on the other hand, when the concentration of ammonium is high or when other ‘good’ nitrogen sources like glutamine or asparagine are supplied in the culture medium. The overall properties of Mep1p indicate that it is a transporter of ammonium. Its main function appears to be to enable cells grown under nitrogen‐limiting conditions to incorporate ammonium present at relatively low concentrations in the growth medium.

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Methylamine and ammonia transport in Saccharomyces cerevisiae

Cited by 124 publications

References 14 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

Characterization of Arabidopsis AtAMT2, a novel ammonium transporter in plants

Cloning and expression of the MEP1 gene encoding an ammonium transporter in Saccharomyces cerevisiae.

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