THE MOLECULAR-BIOLOGY OF METAL-ION TRANSPORT IN SACCHAROMYCES-CEREVISIAE

Transition metals such as iron, copper, manganese, and zinc are essent ial nutrients. The yeast Saccharomyces cerevisiae is an ideal organism for deciphering the mechanism and regulation of metal ion transport. Recent studies of yeast have shown that accumulation of any single met al ion is mediated by two or more substrate-specific transport systems . High-affinity systems are active in metal-limited cells, whereas low -affinity systems play the predominant roles when the substrate is mor e abundant. Metal ion uptake systems of cells are tightly controlled, and both transcriptional and posttranscriptional regulatory mechanisms have been identified. Most importantly, studies of S. cerevisiae have identified a large number of genes that function in metal ion transpo rt and have illuminated the existence and importance of gene families that play related roles in these processes in mammals.