Abstract
In excised pro1-1 mutant and corresponding normal type roots of Zea mays L. the uptake and interconversion of [14C]proline, [14C]glutamic acid, [14C]glutamine, and [14C]ornithine and their utilization for protein synthesis was measured with the intention of finding an explanation for the proline requirement of the mutant. Uptake of these four amino acids, with the exception of proline, was the same in mutant and normal roots, but utilization differed. Higher than normal utilization rates for proline and glutamic acid were noted in mutant roots leading to increased CO2 production, free amino acid interconversion, and protein synthesis. Proline was synthesized from either glutamic acid (or glutamine) or ornithine in both mutant and normal roots; it did not accumulate but rather was used for protein synthesis. Ornithine was not a good precursor for proline in either system, but was preferentially converted to arginine and glutamine, particularly in mutant roots. The pro1-1 mutant was thus not deficient in its ability to make proline. Based on these findings, and on the fact that ornithine, arginine, glutamic acid and aspartic acid are elevated as free amino acids in mutant roots, it is suggested that in the pro1-1 mutant proline catabolism prevails over proline synthesis.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Mestichelli L. J., Gupta R. N., Spenser I. D. The biosynthetic route from ornithine to proline. J Biol Chem. 1979 Feb 10;254(3):640–647. [PubMed] [Google Scholar]
- Oaks A. The soluble leucine pool in maize root tips. Plant Physiol. 1965 Jan;40(1):142–149. doi: 10.1104/pp.40.1.142. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Withers L. A., King P. J. Proline: A Novel Cryoprotectant for the Freeze Preservation of Cultured Cells of Zea mays L. Plant Physiol. 1979 Nov;64(5):675–678. doi: 10.1104/pp.64.5.675. [DOI] [PMC free article] [PubMed] [Google Scholar]