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Mg 2 + homeostasis and avoidance of metal toxicity
Author(s) -
Chamgpol Sangpen,
Groisman Eduardo A.
Publication year - 2002
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2002.02917.x
Subject(s) - biology , mutant , intracellular , salmonella enterica , downregulation and upregulation , transcription (linguistics) , transcription factor , homeostasis , enterobacteriaceae , biochemistry , transporter , oxidative stress , gene expression , bacteria , microbiology and biotechnology , gene , escherichia coli , genetics , linguistics , philosophy
Summary Because Mg 2 + is required for a wide variety of cellular functions, its intracellular levels must be tightly regulated. In the Gram‐negative bacterium Salmonella enterica , three transporters mediate Mg 2 + uptake: the P‐type ATPases MgtA and MgtB, whose expression is transcriptionally induced in low Mg 2 + by the Mg 2 + ‐regulated PhoP/PhoQ two‐component system; and CorA, whose transcription is regulated neither by the levels of Mg 2 + nor by the PhoP/PhoQ system. We now report that mutants defective in phoP or in both mgtA and mgtB are hypersensitive to oxidative stress‐dependent Fe (II)‐mediated killing. These mutants display increased iron accumulation and heightened Ni 2 + uptake. Inactivation of the corA gene restored Fe(II) resistance to the phoP mutant and eliminated uptake of Ni 2 + . Neither corA transcription nor CorA protein levels were altered in the phoP mutant, suggesting that CorA alters its activity in response to the presence of PhoP‐regulated determinants. Downregulation of CorA activity in low Mg 2 + environments may enable Salmonella to avoid the uncontrolled influx of toxic metals.