The opportunistic pathogen Pseudomonas aeruginosa causes a wide range of infections, including chronic biofilm infections in the lungs of individuals with cystic fibrosis. We previously found that the inner-membrane protein MgtE can function both as a magnesium transporter and a virulence modulator, although the exact mechanism governing these activities is unclear. To address this issue, we carried out an experimental characterization of P. aeruginosa MgtE and generated a computer-rendered

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... l. Our in silico analysis demonstrated the structural similarity of P. aeruginosa MgtE to that of the crystal structure of MgtE in Thermus thermophilus. Experimentally, we verified that MgtE is not essential for growth and found that it may not be involved directly in biofilm formation, even under low-magnesium conditions. We demonstrated both magnesium transport and cytotoxicity-regulating functions, and showed that magnesiumbinding sites in the connecting helix region of MgtE are vital in coupling these two functions. Furthermore, limiting magnesium environments stimulated mgtE transcriptional responses. Our results suggested that MgtE might play an important role in linking magnesium availability to P. aeruginosa pathogenesis.