Amino acid transport into fungi: An essay

Whitaker, Allan

doi:10.1016/s0007-1536(76)80160-x

Cited by 19 publications

(9 citation statements)

References 105 publications

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“…This suggests that the capacity to use nitrate can be lost by mutation and that survival of strains harboring this mutation is probably governed by their ecological situation rather than their taxonomic position (Whitaker, 1976). According to our knowledge, no isolation is reported on mutants resistant to chlorate in these groups.…”

Section: Discussionmentioning

confidence: 91%

“…It has been pointed out that the inability to utilize nitrates is common among the higher Basidiomycetes, the Saprolegniaceae, the Blastcladiales, and certain members of the Mucorales (Whitaker, 1976). This suggests that the capacity to use nitrate can be lost by mutation and that survival of strains harboring this mutation is probably governed by their ecological situation rather than their taxonomic position (Whitaker, 1976).…”

Section: Discussionmentioning

confidence: 99%

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Isolation and characterization of chlorate resistant mutants from nitrate-nonutilizing fungus Phycomyces blakesleeanus

2000

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Chlorate resistant mutants, which were first isolated in the zygomycetous fungus Phycomyces blakesleeanus, were found to be resistant up to a concentration of at least 300 mM of potassium chlorate. The dose-response relationship showed that although the mutants could be divided into two groups based on chlorate resistance in the mycelial elongation assay on the solid minimal medium, this was not observed in the assay using liquid culture. Genetic analysis of heterokaryons revealed the mutant alleles to be dominant. Enzymatic activities of three nitrate reductases and chlorate reductase were deficient in both the parent strain and the mutants. Intracellular incorporation of chlorate ion varied from strain to strain; however, the variation could not explain the mechanism of chlorate resistance. One unexpected characteristic of the mutants was that the intracellular sulfate ion concentration was 3.5 to 5.5 times higher than in the parent strain. We designated this mutant genotype crw, chlorate resistant mutant from nitrate-nonutilizing wild type.

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Section: Discussionmentioning

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Isolation and characterization of chlorate resistant mutants from nitrate-nonutilizing fungus Phycomyces blakesleeanus

2000

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“…5,16,27). Generally, this appears to be due to derepression of the synthesis of the uptake system (4,8,28).…”

Section: Discussionmentioning

confidence: 99%

Regulation of Development of Leucine Uptake Activity by Glutamine in the Scutellum of Germinating Barley Grain

Nyman

Sopanen²,

Mikola³

1983

Plant Physiol.

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Scutella from ungerminated grains of barley (Hordeum vulgare L. cv Pirkka) take up leucine at a slow rate, which increases rapidly during germination. When endosperms were removed from the gains after imbibition for 4 hours or after germination for 12 or 72 hours, the increase in the rate of leucine uptake was greatly accelerated during subsequent incubation of the embryos or scutella. These increases were rapidly inhibited by cordycepin and cycloheximide, suggesting that protein synthesis, probably synthesis of the carrier protein, was required for the development of the uptake activity.In separated embryos or scutella, the increases in the leucine uptake activity were inhibited by glutamine. The inhibitions caused by glutamine and cycloheximide were not additive, suggesting that glutamine did not interfere with the function of the carrier but repressed its synthesis. Glutamine did not inhibit the simultaneous increase in peptide uptake; in this respect, its effect was specific for leucine uptake, which appears to be due to a general amino acid uptake system. Some other protein amino acids also inhibited the increase in leucine uptake without inhibiting the increase in peptide uptake. However, these effects were smaller than that of glutamine.These results suggest that the transfer of leucine (and other amino acids) from the endosperm to the seedling in a germinating barley grain is regulated at the uptake step by repression of the synthesis of the amino acid carrier protein by glutamine and-possibly to a lesser extent-by some other amino acids taken up from the endosperm.The hydrolysis of reserve proteins in the starchy endosperm of a germinating barley grain results in a mixture of free amino acids and short oligopeptides (7,13,14,20). The amino acids and peptides are taken up into the scutellum by separate transport systems (6,11,(20)(21)(22). We have previously studied some properties of amino acid uptake into the scutellum using leucine as the substrate (24). Leucine is rapidly taken up by an active transport system(s), the rate of uptake being highest near pH 5, the pH of the starchy endosperm (14).The uptake of leucine is slow in scutella separated from ungerminated grains, but increases about 10-fold during the first 3 d ofgermination of whole grains (24). This increase is followed by a lag phase of about 1 d, after which there is another increase.Removal of the embryonic axis has no effect on the initial ' Supported by the Research Council for Natural Sciences of which T. S. is a Research Fellow. The work was also supported by a grant from the Emil Aaltonen foundation to S. N.2 Abbreviations: CHI, cycloheximide; Sar, sarcosine; COR, cordycepin; AIB, a-amino-iso-butyric acid.increase in the rate of uptake (24). On the other hand, removal of the endosperm either after imbibition for 4 h or after germination for 3 d enhances the rate ofthe increase during subsequent incubation. In both cases, the increase is completely prevented by CHI2 and markedly slowed down by glutamine. It was therefore su...

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“…To study the kinetics of ACV synthetase, e.g. determine the maximum capacity and affinity constants [7,8] or the secretion mechanism, which requires measurement of the concentration gradient over the cell membrane, it is essential to have accurate measurements of the intra-and extra-cellular ACV levels [9,10]. As ACV is spontaneously oxidized by the attachment to other thiolcontaining metabolites, accurate quantification can only be performed if the free reduced form is protected at the time of sampling, and further oxidation during sample processing is prevented.…”

Section: Introductionmentioning

confidence: 99%

Determination of δ‐[L‐α‐aminoadipyl]‐L‐cysteinyl‐D‐valine in cell extracts of Penicillium chrysogenum using ion pair‐RP‐UPLC‐MS/MS

Seifar

Deshmukh

Heijnen

et al. 2012

J of Separation Science

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δ-[L-α-Aminoadipyl]-L-cysteinyl-D-valine (ACV) is a key intermediate in the biosynthesis pathway of penicillins and cephalosporins. Therefore, the accurate quantification of ACV is relevant, e.g. for kinetic studies on the production of these β-lactam antibiotics. However, accurate quantification of ACV is a challenge, because it is an active thiol compound which, upon exposure to air, can easily react with other thiol compounds to form oxidized disulfides. We have found that, during exposure to air, the oxidation of ACV occurs both in aqueous standard solutions as well as in biological samples. Qualitative and quantitative determinations of ACV and the oxidized dimer bis-δ-[L-α-aminoadipyl]-L-cysteinyl-D-valine have been carried out using ion pair reversed-phase ultra high-performance liquid chromatography, hyphenated with tandem mass spectrometry (IP-RP-UPLC-MS/MS) as the analytical platform. We show that by application of tris(2-carboxy-ethyl)phosphine hydrochloride (TCEP) as the reducing reagent, the total amount of ACV can be determined, while using maleimide as derivatizing reagent enables to quantify the free reduced form only.

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Amino acid transport into fungi: An essay

Cited by 19 publications

References 105 publications

Isolation and characterization of chlorate resistant mutants from nitrate-nonutilizing fungus Phycomyces blakesleeanus

Isolation and characterization of chlorate resistant mutants from nitrate-nonutilizing fungus Phycomyces blakesleeanus

Regulation of Development of Leucine Uptake Activity by Glutamine in the Scutellum of Germinating Barley Grain

Determination of δ‐[L‐α‐aminoadipyl]‐L‐cysteinyl‐D‐valine in cell extracts of Penicillium chrysogenum using ion pair‐RP‐UPLC‐MS/MS

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