Hexose uptake in the plant symbiotic ascomycete Tuber borchii Vittadini: biochemical features and expression pattern of the transporter TBHXT1

Sugar transporters in the black truffle Tuber melanosporum: from gene prediction to functional characterization

“…The sequences were further analyzed using fungal sugar proteins with proven hexose import capability as a template (Boles and Hollenberg, 1997;Helber et al, 2011;López et al, 2008;Nehls et al, 1998;Polidori et al, 2007;Wieczorke et al, 1999). For the three GSTUMTs characterized in this investigation, the BLAST search was also extended to the Ascomycota genomes available at the fungal genomic portal MycoCosm (http://jgi.doe.gov/fungi) (Grigoriev et al, 2014).…”

“…Ten microliters of each reaction mixture were used for the evaluation of the total radioactivity, while the remaining samples were incubated at 30°C for 1 min. All uptake experiments were performed following the procedures described in Polidori et al (2007) and were repeated with independent samples at least three times. The kinetic parameters were determined using the Lineweaver-Burke plot, and all the data were analyzed by nonlinear regression using the Enz-Fitter program.…”

“…Among Tuber species, Tbhxt1 from Tuber borchii is the first high affinity glucose transporter that has been identified. Considering the expression pattern of the Tbhxt1 gene and the kinetic characteristics of the encoded protein, it is mainly responsible for carbohydrate uptake by soil-growing hyphae and the reduction of sugar leakage from hyphae and is not associated with the symbiotic process (Polidori et al, 2007). The large gap in our knowledge regarding hexose import into ECM was bridged by López et al (2008), who identified 15 potential sugar transporter proteins in the genome of the basidiomycete ectomycorrhizal fungus Laccaria bicolor.…”

Organic acid production in Aspergillus niger and other filamentous fungi

“…These yeast mutant strains, unable to grow on glucose, fructose, mannose and galactose as a single carbon source, have also subsequently been used as tools for the functional characterisation of sugar transporters from other fungal species (Colabardini et al, 2014;dos Reis et al, 2013;Du et al, 2010;Leandro et al, 2013;Polidori et al, 2007;Saloheimo et al, 2007;Vankuyk PA et al, 2004;Wahl et al, 2010) In contrast to S. cerevisiae, the only functionally validated sugar transporters in A. niger are the recently identified D-galacturonic acid transporter GatA (Martens-Uzunova and Schaap, 2008;Sloothaak et al, 2014), two fructose transporters (Coelho et al, 2013) and the high-affinity sugar/H + symporter MstA (Vankuyk PA et al, 2004). Furthermore, transcriptional data for the A. niger mstC gene suggests that it encodes a low-affinity glucose transporter (Jørgensen et al, 2007), but no experimental data supporting its role as a functional sugar transporter is publicly available.…”

“…Yeast transporter null mutants were subsequently also used for the functional characterization of sugar porters from other fungal species (dos Reis et al, 2013;Du et al, 2010;Leandro et al, 2013;Polidori et al, 2007;Saloheimo et al, 2007;Vankuyk PA et al, 2004).…”