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Regulation of hypoxanthine transport in Neurospora crassa

, : Regulation of hypoxanthine transport in Neurospora crassa. Journal of Bacteriology 128(2): 598-603

Hypoxanthine uptake and hypoxanthine phosphoribosyltransferase activity (EC were determined in germinated conidia from the adenine auxotrophic strains ad-1 and ad-8 and the double mutant strain ad-1 ad-8. The mutant strain ad-1 appears to lack aminoimidazolecarboximide ribonucleotide formyltransferase (EC or inosine 5'monophosphate cyclohydrolase (EC activities, or both, whereas the ad-8 strain lacks adenylosuccinate synthase activity (EC Normal (or wild-type) hypoxanthine transport capacity was found to the ad-1 conidia, whereas the ad-8 strains failed to take up any hypoxanthine. The double mutant strains showed intermediate transport capacities. Similar results were obtained for hypoxanthine phosphoribosyl-transferase activity assayed in germinated conidia. The ad-1 strain showed greatest activity, the ad-8 strain showed the least activity, and the double mutant strain showed intermediate activity levels. Ion-exchange chromatography of the growth media revealed that in the presence of NH+/4, the ad-8 strain excreted hypoxanthine or inosine, the ad-1 strain did not excrete any purines, and the ad-1 ad-8 double mutant strain excreted uric acid. In the absence of NH+/4, none of the strains excreted any detectable purine compounds.

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Accession: 041211166

PMID: 135758

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Related references

Pall, M.L., 1971: Amino acid transport in Neurospora crassa. IV. Properties and regulation of a methionine transport system. A specific amino acid transport system in Neurospora crassa is described with affinity for methionine and several of its analogs. This methionine transport system has a Michaelis constant (Km) for l-methionine of about 23 M and has lower affinity...

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