Uptake and translocation of 2-aminoisobutyric acid by Schizophyllum commune

• Published in: Experimental mycology Vol. 14; no. 2; pp. 169 - 177
• Main Authors: Lilly, Walt W., Higgins, Sean M., Wallweber, Gerald J.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.01.1990; Academic Press
• Subjects: 2-aminoisobutyric acid; amino acid pools; amino acid translocation; amino acid uptake; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Growth, nutrition, metabolism, transports, enzymes. Molecular biology; Microbiology; Mycology; Schizophyllum commune; Schizophyllum commune; amino acid translocation; 2-aminoisobutyric acid; amino acid pools; amino acid uptake; Fungi; Culture medium; Translocation; Radiolabelling; Membrane transport; Aminoacid; Basidiomycetes; Uptake; Thallophyta
• ISSN: 0147-5975; 1878-4399
• DOI: 10.1016/0147-5975(90)90075-5

The nonnative amino acid, 2-aminoisobutyric acid (AIB), is transported into homokaryotic mycelia of Schizophyllum commune. However, because it is neither incorporated into protein nor further metabolized by the fungal cells, it may be used as a marker for the free amino acid pool. Colonies grown or maintained under nitrogen-limiting conditions show enhanced uptake and higher concentrations of AIB in the mycelium than controls. Based on growth inhibition and uptake kinetic experiments, the enhanced uptake appears to be the result of decreased competition for a common uptake channel with l-asparagine normally found in the medium. Colonies containing radiolabeled AIB show translocation of the label to growing hyphal apices when they are transferred to unlabeled nitrogen-deficient media. Chases on nitrogen-rich media do not result in translocation of the label. In contrast to colonies chased on nitrogen-rich media, nitrogen deprivation does not lead to release of significant amounts of AIB into the medium by older cells. This supports an intramycelial pathway for translocation of pool amino acids.