Novel Evolutionary Engineering Approach to Alter Substrate Specificity of Disaccharide Transporter Mal11 in Saccharomyces cerevisiae

A major challenge in the research of transport proteins is to understand how single amino acid residues contribute to their structure and biological function. Amino acid substitutions that result in a selective advantage in adaptive laboratory evolution experiments can provide valuable hints at their role in transport proteins. In this study, we...

Pathway engineering strategies for improved product yield in yeast-based industrial ethanol production

Product yield on carbohydrate feedstocks is a key performance indicator for industrial ethanol production with the yeast Saccharomyces cerevisiae. This paper reviews pathway engineering strategies for improving ethanol yield on glucose and/or sucrose in anaerobic cultures of this yeast by altering the ratio of ethanol production, yeast growth...

Carbon dioxide fixation via production of succinic acid from glycerol in engineered Saccharomyces cerevisiae

Background: The microbial production of succinic acid (SA) from renewable carbon sources via the reverse TCA (rTCA) pathway is a process potentially accompanied by net-fixation of carbon dioxide (CO₂). Among reduced carbon sources, glycerol is particularly attractive since it allows a nearly twofold higher CO₂-fixation...

Engineering proton-coupled hexose uptake in Saccharomyces cerevisiae for improved ethanol yield

Background: In the yeast Saccharomyces cerevisiae, which is widely applied for industrial bioethanol production, uptake of hexoses is mediated by transporters with a facilitated diffusion mechanism. In anaerobic cultures, a higher ethanol yield can be achieved when transport of hexoses is proton-coupled, because of the lower net ATP yield of...

Evolutionary engineering reveals amino acid substitutions in Ato2 and Ato3 that allow improved growth of Saccharomyces cerevisiae on lactic acid

In Saccharomyces cerevisiae, the complete set of proteins involved in transport of lactic acid across the cell membrane has not been determined. In this study, we aimed to identify transport proteins not previously described to be involved in lactic acid transport via a combination of directed evolution, whole-genome resequencing and reverse...

Energy coupling of membrane transport and efficiency of sucrose dissimilation in yeast

Proton coupled transport of α-glucosides via Mal11 into Saccharomyces cerevisiae costs one ATP per imported molecule. Targeted mutation of all three acidic residues in the active site resulted in sugar uniport, but expression of these mutant transporters in yeast did not enable growth on sucrose. We then isolated six unique transporter...