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Mutants Affecting Thymidine Metabolism in Neurospora crassa

Williams, Larry G. and Mitchell, H. K. (1969) Mutants Affecting Thymidine Metabolism in Neurospora crassa. Journal of Bacteriology, 100 (1). pp. 383-389. ISSN 0021-9193. PMCID PMC315404.

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When 14C-thymidine labeled only in the ring is administered to Neurospora crassa, the majority of the recovered label is found in the ribonucleic acid (RNA). Three mutants were isolated in which different steps are blocked in the pathway that converts the pyrimidine ring of thymidine to an RNA precursor. Evidence from genetic, nutritional, and accumulation studies with the three mutants shows the pathway to proceed as follows: thymidine -> thymine -> 5-hydroxymethyluracil -> 5-formyluracil -> uracil -> uridylic acid. A mutant strain in which the thymidine to thymine conversion is blocked is unable to metabolize thymidine appreciably by any route, including entry into nucleic acids. This suggests that Neurospora lacks a thymidine phosphorylating enzyme. A second mutation blocks the pathway at the 5-hydroxymethyluracil to 5-formyluracil step, whereas a third prevents utilization of uracil and all compounds preceding it in the pathway. The mutant isolation procedures yielded three other classes of mutations which are proposed to be affecting, respectively, regulation of the thymidine degradative pathway, transport of pyrimidine free bases, and transport of pyrimidine nucleosides.

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Additional Information:© 1969 American Society for Microbiology. Received for publication 8 July 1969 We thank Mogens Westergaard for acquainting us with the problem of thymidine metabolism in Neurospora, and Ruth Williams for her technical assistance.
Issue or Number:1
PubMed Central ID:PMC315404
Record Number:CaltechAUTHORS:WILjbact69
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Official Citation:Mutants Affecting Thymidine Metabolism in Neurospora crassa Larry G. Williams, H. K. Mitchell Journal of Bacteriology Oct 1969, 100 (1) 383-38
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:6200
Deposited By: Archive Administrator
Deposited On:28 Nov 2006
Last Modified:02 Oct 2019 23:30

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