Evolution of an Escherichia coli Protein with Increased Resistance to Oxidative Stress

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1998Author
Lu, Zhe
Obradors, Núria
Aguilar, Juan
Lin, Edmund C. C.
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Lu, Zhe;
Cabiscol Català, Elisa;
Obradors, Núria;
Tamarit Sumalla, Jordi;
Ros Salvador, Joaquim;
Aguilar, Juan;
Lin, Edmund C. C.;
.
(1998)
.
Evolution of an Escherichia coli Protein with Increased Resistance to Oxidative Stress.
Journal of Biological Chemistry, 1998, Vol. 273, núm. 14, p. 8308-8316.
https://doi.org/10.1074/jbc.273.14.8308.
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L-1,2-Propanediol:NAD1 1-oxidoreductase of Escherichia
coli is encoded by the fucO gene, a member of the
regulon specifying dissimilation of L-fucose. The enzyme
normally functions during fermentative growth to regenerate
NAD from NADH by reducing the metabolic
intermediate L-lactaldehyde to propanediol which is excreted.
During aerobic growth L-lactaldehyde is converted
to L-lactate and thence to the central metabolite
pyruvate. The wasteful excretion of propanediol is minimized
by oxidative inactivation of the oxidoreductase,
an Fe21-dependent enzyme which is subject to metalcatalyzed
oxidation (MCO). Mutants acquiring the ability
to grow aerobically on propanediol as sole carbon
and energy source can be readily selected. These mutants
express the fucO gene constitutively, as a result of
an IS5 insertion in the promoter region. In this study we
show that continued selection for aerobic growth on
propanediol resulted in mutations in the oxidoreductase
conferring increased resistance to MCO. In two independent
mutants, the resistance of the protein was
respectively conferred by an Ile7 3 Leu and a Leu8 3 Val
substitution near the NAD-binding consensus amino
acid sequence. A site-directed mutant protein with both
substitutions showed an MCO resistance greater than
either mutant protein with a single amino acid change.