Identification of a Putative P-Type ATPase Involved in Zinc and Cadmium Resistance in Enterobacter sp. YSU

Abstract

The Y-12 plant in Oak Ridge Tennessee was involved in manufacturing and storing nuclear weapon for the last 60 years of the 20th century. These activities led to the contamination of the nearby East Fork Poplar creek from which Enterobacter sp. YSU was isolated and screened for metal resistance genes. Three main previously identified metal resistance mechanisms are efflux, detoxification and sequestration. This bacterium was found to be resistant to several heavy metals including zinc, cadmium, mercury, copper, gold, chromium, silver and selenite. The goal of this study was to identify the gene encoding zinc and cadmium resistance in Enterobacter sp. YSU. Two mutants, EI24 and F24 were created using a transposon which disrupted a P-type ATPase believed to be responsible for these resistances. Minimal Inhibitory Concentrations (MICs) of the mutants were carried out to establish the phenotype of the mutants. These MICs revealed that the mutants were sensitive to toxic concentrations of zinc and cadmium while the wildtype bacterium was not. Gene rescue was carried out to rescue the disrupted gene and this was sequenced to determine its identity. BLAST identified the gene as a P-type ATPase with 97% similarity to a zinc/cadmium/mercury/lead translocating P-type ATPase in Enterobacter.