The Molecular Basis of Acinetobacter baumannii Cadmium Toxicity and Resistance
Saleh F. Alquethamy, Felise G. Adams, Ram P. Maharjan, Natasha N. Delgado, Maoge Zang, Katherine Ganio, James C. Paton, Karl A. Hassan, Ian T. Paulsen, Christopher A. McDevitt, Amy K. Cain, Bart A. Eijkelkamp
Abstract
Cadmium toxicity is a widespread problem, yet the interaction of this heavy metal with biological systems is poorly understood. Some microbes have evolved traits to proactively counteract cadmium toxicity, including Acinetobacter baumannii, which is notorious for persisting in harsh environments. Here, we show that A. baumannii utilizes a dedicated cadmium efflux protein in concert with a system that is primarily attuned to zinc efflux to efficiently overcome cadmium stress. The molecular characterization of A. baumannii under cadmium stress revealed how active cadmium efflux plays a key role in preventing the dysregulation of bacterial metal ion homeostasis, which appeared to be a primary means by which cadmium exerts toxicity upon the bacterium.