Isolation and characterization of a general amino acid permease from the ectomycorrhizal fungus Amanita muscaria

• Published in: The New phytologist Vol. 144; no. 2; pp. 343 - 349
• Main Authors: NEHLS, UWE, KLEBER, REGINE, WIESE, JOACHIM, HAMPP, RÜDIGER
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.11.1999; Blackwell
• Subjects: Agronomy. Soil science and plant productions; AmAAP1 gene; Amanita; Amanita muscaria; amino acid permease; Amino acid transport systems; amino acid transporter; Amino acids; basidiomycete; Biological and medical sciences; Cell physiology; Complementary DNA; Economic plant physiology; Fundamental and applied biological sciences. Psychology; Fungi; gene expression; Nitrates; Plant physiology and development; Plasma membrane and permeation; Quaternary ammonium compounds; RNA; Saccharomyces cerevisiae; Symbiosis (nodules, symbiotic nitrogen fixation, mycorrhiza...); transport; Yeasts; basidiomycete; transport; fungi; gene expression; N; Symbiosis; Nucleotide sequence; Amanita muscaria; Phylogenetic tree; Basidiomycetes; Gene expression; Fungi; Characterization; Regulation(control); Gene; Membrane transport; Poisonous fungi; Aminoacid; Mycorrhiza; Ectomycorrhiza; Isolation; Thallophyta
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1046/j.1469-8137.1999.00513.x

A cDNA coding for a fungal amino acid transporter (AmAAP1) was identified from Amanita muscaria ectomycorrhizas. The transporter gene was expressed at a basal level under all conditions investigated, but its expression was enhanced 10-fold in the absence of a N source utilized by the fungus. Nitrate was not a suitable N source for A. muscaria and resulted in maximal AmAAP1 expression. The expression of AmAAP1 in a yeast mutant revealed its function as a high-affinity amino acid transporter with a broad substrate spectrum. AmAAP1 takes up all investigated amino acids with Km values between 22 μM for histidine and up to 100 μM for proline. Gene expression and amino acid uptake data together indicate two main functions for AmAAP1: uptake of amino acids from soil for fungal nutrition, and prevention of an amino acid loss by hyphal leakage in the absence of a suitable N source.