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Mol Microbiol. 2011 Dec;82(5):1291-300. doi: 10.1111/j.1365-2958.2011.07891.x. Epub 2011 Nov 8.

Fructose-1,6-bisphosphate aldolase (class II) is the primary site of nickel toxicity in Escherichia coli.

Author information

1
Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824-4320, USA.

Abstract

Nickel is toxic to all forms of life, but the mechanisms of cell damage are unknown. Indeed, environmentally relevant nickel levels (8 µM) inhibit wild-type Escherichia coli growth on glucose minimal medium. The same concentration of nickel also inhibits growth on fructose, but not succinate, lactate or glycerol; these results suggest that fructose-1,6-bisphosphate aldolase (FbaA) is a target of nickel toxicity. Cells stressed by 8 µM Ni(II) for 20 min lost 75% of their FbaA activity, demonstrating that FbaA is inactivated during nickel stress. Furthermore, overexpression of fbaA restored growth of an rcnA mutant in glucose minimal medium supplemented with 4 µM Ni(II), thus confirming that FbaA is a primary target of nickel toxicity. This class II aldolase has an active site zinc and a non-catalytic zinc nearby. Purified FbaA lost 80 % of its activity within 2 min when challenged with 8 µM Ni(II). Nickel-challenged FbaA lost 0.8 zinc and gained 0.8 nickel per inactivated monomer. FbaA mutants (D144A and E174A) affecting the non-catalytic zinc were resistant to nickel inhibition. These results define the primary site of nickel toxicity in E. coli as the class II aldolase FbaA through binding to the non-catalytic zinc site.

PMID:
22014167
PMCID:
PMC3225726
DOI:
10.1111/j.1365-2958.2011.07891.x
[Indexed for MEDLINE]
Free PMC Article

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