Nickel resistance in fission yeast associated with the magnesium transport system

Abstract

We isolated and characterized a nickel (Ni2+)-resistant mutant (GAI) of Schizosaccharomyces pombe. This mutant strain displayed resistance to both Ni2+ and Zn2+, but not to Cd2+, Co2+, and CU2+. The growth rate of GAI increased proportionally with increasing Mg2+ concentrations until 50 nM Mg2+. The GAI mutation phenotype Suggests a defect in Mg2+ uptake. Sequence analysis of the GAI open reading frame (ORF) 013779, which is homologous to the prokaryotic and eukaryotic CorA Mg2+ transport systems, revealed a point mutation at codon 153 (ccc to ace) resulting in a Pro 153Thr substitution in the N-terminus of the CorA domain. Our results provide novel genetic information about Ni2+ resistance in fission yeast. Specifically, that reducing Mg2+ influx through the CorA Mg2+ transport membrane protein confers Ni2+ resistance in S. pombe. We also report that Ni2+ ion detoxification of the fission yeast is related to histidine metabolism and pH.