Promotion of Zn2+ Uptake by Al3+ in a Saccharomyces Cerevisiae Mutant that Lacks the ZRT1 Gene Encoding a High-Affinity Zn Transporter

摘要

A Saccharomyces cerevisiae mutant (zrt1Δ) lacking the ZRT1 gene, which encodes a high-affinity Zn2+ transporter, scarcely thrived in a low-pH, low-phosphate medium because of Zn2+ deficiency. Supplementation of the medium with Al3+ restored growth to a level comparable to that of a wild-type strain. A metal determination study clearly demonstrated that Al3+ induced the incorporation of Zn2+ into zrt1Δ cells, probably through the low-affinity Zn2+ transporter Zrt2p, given that the zrt1Δzrt2Δ double mutant did not show Al-induced growth enhancement. Al3+ may have altered the speciation of Zn2+ in the medium, resulting in enhanced levels of free Zn2+. Alternatively, it might be that Zrt2p was degraded by endocytosis in the absence of Al3+ and Al3+ interfered with this process, resulting in enhanced Zn2+ accumulation.