Oxygen- and Glucose-Dependent Expression of Trhxt1, a Putative Glucose Transporter Gene of Trichoderma reesei^,

Abstract

The filamentous fungus Trichoderma reesei is adapted to nutrient-poor environments, in which it uses extracellular cellulases to obtain glucose from the available cellulose biomass. We have isolated and characterized Trhxt1, a putative glucose transporter gene, as judged by the glucose accumulation phenotype of a DeltaTrhxt1 mutant. This gene is repressed at high glucose concentrations and expressed at micromolar levels and in the absence of glucose. The gene is also induced during the growth of T. reesei on cellulose when the glucose concentration generated from the hydrolysis of cellulose present in the culture medium is in the micromolar range. We also show that oxygen availability controls the expression of the Trxht1 gene. In this regard, the gene is down-regulated by hypoxia and also by the inhibition of the flow of electrons through the respiratory chain using antimycin A. Intriguingly, anoxia but not hypoxia strongly induces the expression of the gene in the presence of an otherwise repressive concentration of glucose. These results indicate that although the absence of repressing concentrations of glucose and an active respiratory chain are required for Trhxt1 expression under normoxic conditions these physiological processes have no effect on the expression of this gene under an anoxic state. Thus, our results highlight the presence of a novel coordinated interaction between oxygen and the regulatory circuit for glucose repression under anoxic conditions.

Correlation of gene expression and protein production rate - a system wide study

“…Of the chromosomal clusters with positive correlation to SPPR, three contain typical secondary metabolism genes (c1: non-ribosomal peptide synthase; c9: polyketide synthase; c7: trichothecene C-15 hydroxylase homologue [49] ). Four contain carbon source degradation and uptake related genes (c2: xyn1 [50], ThPg1 [51] homologue and two other CAZymes; c3: trhxt1 [52] and three other putative transporters; c6: glucose-methanol-choline (GMC) oxidoreductase; c7: cbh1 [53] and three putative transporters). Of these c1, c6 and c9 contain putative transcription factors of the Zn2Cys6-family.…”

A novel major facilitator transporter TrSTR1 is essential for pentose utilization and involved in xylanase induction in Trichoderma reesei

“…harzianum. The characterized hexose transporter TrHXT1 [20] and xylose transporter TrXLT1 [9] in T. reesei are also in this cluster, suggesting that TrSTR1 is a putative monosaccharide transporter.…”

Organic acid production in Aspergillus niger and other filamentous fungi

“…In this regard, the A. niger analyzing the T. reesei transcriptomic response to wheat straw, many of the HMM xylT top scoring transporters were upregulated on this carbon source versus glucose (Bischof et al, 2013;Ries et al, 2013). We also found that the function of three of the top scoring transporters had been studied previously (Huang et al, 2015;Ramos et al, 2006;Saloheimo et al, 2007;Zhang et al, 2013). One of them, TrStr1 (protID 50894) (Huang et al, 2015) was confirmed to function as xylose transporter, while Stp1 (protID 47710) and TrHxt1 (protID 22912) were associated to cellobiose and glucose utilization respectively (Ramos et al, 2006;Zhang et al, 2013).…”

“…We also found that the function of three of the top scoring transporters had been studied previously (Huang et al, 2015;Ramos et al, 2006;Saloheimo et al, 2007;Zhang et al, 2013). One of them, TrStr1 (protID 50894) (Huang et al, 2015) was confirmed to function as xylose transporter, while Stp1 (protID 47710) and TrHxt1 (protID 22912) were associated to cellobiose and glucose utilization respectively (Ramos et al, 2006;Zhang et al, 2013).…”