Evidence for rapid uptake of D-galacturonic acid in the yeast Saccharomyces cerevisiae by a channel-type transport system.
D-Galacturonic acid is a major component of pectins but cannot be metabolized by Saccharomyces cerevisiae. It is assumed not to be taken up. We show that yeast displays surprisingly rapid low-affinity uptake of D-galacturonic acid, strongly increasing with decreasing extracellular pH and without saturation up to 1.5 M. There was no intracellular concentration above the extracellular level and transport was reversible. Among more than 160 single and multiple deletion mutants in channels and transporters, no strain was affected in D-galacturonic acid uptake. The uptake was not inhibited by any compound tested as candidate competitive inhibitor, including D-glucuronic acid, which was also transported. The characteristics of D-galacturonic acid uptake are consistent with involvement of a channel-type system, probably encoded by multiple genes.
Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Flanders, Belgium.
Ben
B
Souffriau
Tom
T
den Abt
Johan M
JM
Thevelein
D019297:2,4-Dinitrophenol / Q000378:metabolism; D000838:Anions; D001692:Biological Transport; D003486:Cyanides / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000737:chemistry; D017353:Gene Deletion; D005786:Gene Expression Regulation; D015966:Gene Expression Regulation, Fungal; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006603:Hexuronic Acids / Q000737:chemistry / Q000493:pharmacokinetics*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D013379:Substrate Specificity; D013997:Time Factors
D000838:Anions; D003486:Cyanides; D006603:Hexuronic Acids; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins; D000431:Ethanol; C007819:galacturonic acid; D019297:2,4-Dinitrophenol