Metalloid tolerance based on phytochelatins is not functionally equivalent to the arsenite transporter Acr3p.
Active transport of metalloids by Acr3p and Ycf1p in Saccharomyces cerevisiae and chelation by phytochelatins in Schizosaccharomyces pombe, nematodes, and plants represent distinct strategies of metalloid detoxification. In this report, we present results of functional comparison of both resistance mechanisms. The S. pombe and wheat phytochelatin synthase (PCS) genes, when expressed in S. cerevisiae, mediate only modest resistance to arsenite and thus cannot functionally compensate for Acr3p. On the other hand, we show for the first time that phytochelatins also contribute to antimony tolerance as PCS fully complement antimonite sensitivity of ycf1Delta mutant. Remarkably, heterologous expression of PCS sensitizes S. cerevisiae to arsenate, while ACR3 confers much higher arsenic resistance in pcsDelta than in wild-type S. pombe. The analysis of PCS and ACR3 homologues distribution in various organisms and our experimental data suggest that separation of ACR3 and PCS genes may lead to the optimal tolerance status of the cell.
Wysocki
Robert
R
Institute of Genetics and Microbiology, Wroclaw University, Przybyszewskiego 63/77, 51-148, Wroclaw, Poland.
Clemens
Stephan
S
Augustyniak
Daria
D
Golik
Pawel
P
Maciaszczyk
Ewa
E
Tamás
Markus J
MJ
Dziadkowiec
Dorota
D
D019881:Aminoacyltransferases / Q000145:classification / Q000235:genetics / Q000502:physiology*; D000965:Antimony / Q000494:pharmacology; D001151:Arsenic / Q000494:pharmacology; D018053:Arsenites / Q000378:metabolism; D001693:Biological Transport, Active; D025141:Drug Resistance, Fungal; D005978:Glutathione; D008565:Membrane Proteins / Q000145:classification / Q000502:physiology*; D026901:Membrane Transport Proteins / Q000145:classification / Q000502:physiology*; D008667:Metalloproteins / Q000502:physiology; D008670:Metals / Q000494:pharmacology*; D009154:Mutation; D010802:Phylogeny; D054811:Phytochelatins; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D012568:Schizosaccharomyces / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D015003:Yeasts / Q000187:drug effects*
C109281:ACR3 protein, S cerevisiae; D018053:Arsenites; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D008667:Metalloproteins; D008670:Metals; D029701:Saccharomyces cerevisiae Proteins; D054811:Phytochelatins; D000965:Antimony; D019881:Aminoacyltransferases; C093784:glutathione gamma-glutamylcysteinyltransferase; D005978:Glutathione; C015001:arsenite; D001151:Arsenic