Functional characterization of a highly specific L-arabinose transporter from Trichoderma reesei.
Options
BORIS DOI
Publisher DOI
PubMed ID
34496831
Description
BACKGROUND
Lignocellulose biomass has been investigated as a feedstock for second generation biofuels and other value-added products. Some of the processes for biofuel production utilize cellulases and hemicellulases to convert the lignocellulosic biomass into a range of soluble sugars before fermentation with microorganisms such as yeast Saccharomyces cerevisiae. One of these sugars is L-arabinose, which cannot be utilized naturally by yeast. The first step in L-arabinose catabolism is its transport into the cells, and yeast lacks a specific transporter, which could perform this task.
RESULTS
We identified Trire2_104072 of Trichoderma reesei as a potential L-arabinose transporter based on its expression profile. This transporter was described already in 2007 as D-xylose transporter XLT1. Electrophysiology experiments with Xenopus laevis oocytes and heterologous expression in yeast revealed that Trire2_104072 is a high-affinity L-arabinose symporter with a Km value in the range of [Formula: see text] 0.1-0.2 mM. It can also transport D-xylose but with low affinity (Km [Formula: see text] 9 mM). In yeast, L-arabinose transport was inhibited slightly by D-xylose but not by D-glucose in an assay with fivefold excess of the inhibiting sugar. Comparison with known L-arabinose transporters revealed that the expression of Trire2_104072 enabled yeast to uptake L-arabinose at the highest rate in conditions with low extracellular L-arabinose concentration. Despite the high specificity of Trire2_104072 for L-arabinose, the growth of its T. reesei deletion mutant was only affected at low L-arabinose concentrations.
CONCLUSIONS
Due to its high affinity for L-arabinose and low inhibition by D-glucose or D-xylose, Trire2_104072 could serve as a good candidate for improving the existing pentose-utilizing yeast strains. The discovery of a highly specific L-arabinose transporter also adds to our knowledge of the primary metabolism of T. reesei. The phenotype of the deletion strain suggests the involvement of other transporters in L-arabinose transport in this species.
Lignocellulose biomass has been investigated as a feedstock for second generation biofuels and other value-added products. Some of the processes for biofuel production utilize cellulases and hemicellulases to convert the lignocellulosic biomass into a range of soluble sugars before fermentation with microorganisms such as yeast Saccharomyces cerevisiae. One of these sugars is L-arabinose, which cannot be utilized naturally by yeast. The first step in L-arabinose catabolism is its transport into the cells, and yeast lacks a specific transporter, which could perform this task.
RESULTS
We identified Trire2_104072 of Trichoderma reesei as a potential L-arabinose transporter based on its expression profile. This transporter was described already in 2007 as D-xylose transporter XLT1. Electrophysiology experiments with Xenopus laevis oocytes and heterologous expression in yeast revealed that Trire2_104072 is a high-affinity L-arabinose symporter with a Km value in the range of [Formula: see text] 0.1-0.2 mM. It can also transport D-xylose but with low affinity (Km [Formula: see text] 9 mM). In yeast, L-arabinose transport was inhibited slightly by D-xylose but not by D-glucose in an assay with fivefold excess of the inhibiting sugar. Comparison with known L-arabinose transporters revealed that the expression of Trire2_104072 enabled yeast to uptake L-arabinose at the highest rate in conditions with low extracellular L-arabinose concentration. Despite the high specificity of Trire2_104072 for L-arabinose, the growth of its T. reesei deletion mutant was only affected at low L-arabinose concentrations.
CONCLUSIONS
Due to its high affinity for L-arabinose and low inhibition by D-glucose or D-xylose, Trire2_104072 could serve as a good candidate for improving the existing pentose-utilizing yeast strains. The discovery of a highly specific L-arabinose transporter also adds to our knowledge of the primary metabolism of T. reesei. The phenotype of the deletion strain suggests the involvement of other transporters in L-arabinose transport in this species.
Date of Publication
2021-09-08
Publication Type
Article
Subject(s)
Keyword(s)
Arabinose transporter Pentose fermentation Transmembrane transport Trichoderma reesei
Language(s)
en
Contributor(s)
Havukainen, Sami | |
Valkonen, Mari | |
Landowski, Christopher P |
Series
Microbial cell factories
Publisher
BioMed Central
ISSN
1475-2859
Access(Rights)
open.access