Potassium and sodium uptake systems in fungi. The transporter diversity of Magnaporthe oryzae

• Published in: Fungal genetics and biology 2011-08, Vol.48 (8), p.812-822
• Main Authors: Benito, Begoña, Garciadeblás, Blanca, Fraile-Escanciano, Ana, Rodríguez-Navarro, Alonso
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphatases - genetics; Adenosine Triphosphatases - metabolism; Ascomycota; Biological Transport; Cation Transport Proteins - genetics; Cation Transport Proteins - metabolism; Fungal Proteins - genetics; Fungal Proteins - metabolism; Fungi; Fungi - classification; Fungi - genetics; Fungi - metabolism; Gene Expression Regulation, Fungal; genes; inventories; leaves; Magnaporthe - genetics; Magnaporthe - growth & development; Magnaporthe - metabolism; Magnaporthe - pathogenicity; Magnaporthe oryzae; Molecular Sequence Data; nucleotide sequences; Oryza - microbiology; Oryza sativa; Phylogeny; Plant Diseases - microbiology; Potassium; Potassium - metabolism; rice; Saccharomyces cerevisiae; Sequence Analysis, DNA; Sodium; Sodium - metabolism; starvation; Transporters
• ISSN: 1087-1845; 1096-0937
• DOI: 10.1016/j.fgb.2011.03.002

► Fungi are furnished with four types of K+ transport systems, TRK and HAK transporters, and ACU and PAT ATPases. ► The distribution of these transport systems is highly variable across fungal species. ► The ACU ATPases of Magnaporthe oryzae mediate high-affinity Na+ uptake in addition to K+ uptake. In this study, we report an inventory of the K+ uptake systems in 62 fungal species for which the complete genome sequences are available. This inventory reveals that three types of K+ uptake systems, TRK and HAK transporters and ACU ATPases, are widely present in several combinations across fungal species. PAT ATPases are less frequently present and are exceptional in Ascomycota. The genome of Magnaporthe oryzae contains four TRK, one HAK, and two ACU genes. The study of the expression of these genes at high K+, K+ starvation, and in infected rice leaves revealed that the expression of four genes, ACU1, ACU2, HAK1, and TRK1 is much lower than that of TRK2, TRK3, and TRK4, except under K+ starvation. The two ACU ATPases were cloned and functionally identified as high-affinity K+ or Na+ uptake systems. These two ATPases endow Saccharomyces cerevisiae with the capacity to grow for several generations in low Na+ concentrations when K+ was absent, which produces a dramatic increase of cellular Na+/K+ ratio.