Abstract
The rate of tryptophan transport in Neurospora is regulated by the intracellular pool of tryptophan. When cells were shifted from growth in minimal medium to tryptophan-containing medium for 10 min, there was a 50% reduction in the rate of tryptophan transport. Intracellular tryptophan pools derived from indole were equally effective in reducing the rate of transport as externally supplied tryptophan. The regulatory influence of tryptophan on the transport system appears to be a property of all the amino acids transported by the tryptophan transport site or sites. Lysine and glutamic acid are not transported by the tryptophan transport site or sites and are ineffective in the regulation of tryptophan uptake. Continued protein synthesis is required for the maintenance of a functional tryptophan transport system. The half-life of the transport system, estimated by inhibiting protein synthesis with cycloheximide, was about 15 min. Turnover of the system occurred at 30 C but not at 4 C, suggesting that the breakdown of the system is enzymatically mediated. It was inferred that the rate of tryptophan transport in Neurospora is modulated through the maintenance of a delicate balance between the synthesis and breakdown of some component of the transport system.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Baker T. I. Tryptophan: a feedback activator for chorismate mutase from Neurospora. Biochemistry. 1966 Aug;5(8):2654–2657. doi: 10.1021/bi00872a025. [DOI] [PubMed] [Google Scholar]
- DEMOSS J. A. Studies on the mechanism of the tryptophan synthetase reaction. Biochim Biophys Acta. 1962 Aug 13;62:279–293. doi: 10.1016/0006-3002(62)90041-0. [DOI] [PubMed] [Google Scholar]
- DEMOSS J. A. THE CONVERSION OF SHIKIMIC ACID TO ANTHRANILIC ACID BY EXTRACTS OF NEUROSPORA CRASSA. J Biol Chem. 1965 Mar;240:1231–1235. [PubMed] [Google Scholar]
- Doy C. H. Tryptophan as an inhibitor of 3-deoxy-arabino-heptulosonate 7-phosphate synthetase. Biochem Biophys Res Commun. 1967 Jan 23;26(2):187–192. doi: 10.1016/0006-291x(67)90232-x. [DOI] [PubMed] [Google Scholar]
- Elsas L. J., Rosenberg L. E. Inhibition of amino Acid transport in rat kidney cortex by puromycin. Proc Natl Acad Sci U S A. 1967 Feb;57(2):371–378. doi: 10.1073/pnas.57.2.371. [DOI] [PMC free article] [PubMed] [Google Scholar]
- JAKOBY W. B., BONNER D. M. Kynureninase from Neurospora: purification and properties. J Biol Chem. 1953 Dec;205(2):699–707. [PubMed] [Google Scholar]
- MATCHETT W. H., DEMOSS J. A. Factors affecting increased production of tryptophan synthetase by a TD mutant of Neurospora crassa. J Bacteriol. 1962 Jun;83:1294–1300. doi: 10.1128/jb.83.6.1294-1300.1962. [DOI] [PMC free article] [PubMed] [Google Scholar]
- MATCHETT W. H., DEMOSS J. A. PHYSIOLOGICAL CHANNELING OF TRYPTOPHAN IN NEUROSPORA CRASSA. Biochim Biophys Acta. 1964 Apr 4;86:91–99. doi: 10.1016/0304-4165(64)90162-x. [DOI] [PubMed] [Google Scholar]
- Piperno J. R., Oxender D. L. Amino-acid-binding protein released from Escherichia coli by osmotic shock. J Biol Chem. 1966 Dec 10;241(23):5732–5734. [PubMed] [Google Scholar]
- Wiley W. R., Matchett W. H. Tryptophan transport in Neurospora crassa. I. Specificity and kinetics. J Bacteriol. 1966 Dec;92(6):1698–1705. doi: 10.1128/jb.92.6.1698-1705.1966. [DOI] [PMC free article] [PubMed] [Google Scholar]