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Hemerythrins in the microaerophilic bacterium C ampylobacter jejuni help protect key iron–sulphur cluster enzymes from oxidative damage
Author(s) -
Kendall John J.,
BarreroTobon Angelica M.,
Hendrixson David R.,
Kelly David J.
Publication year - 2014
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.12341
Subject(s) - microaerophile , biology , enzyme , bacteria , campylobacter jejuni , biochemistry , microbiology and biotechnology , oxygen , chemistry , genetics , organic chemistry
Summary Microaerophilic bacteria are adapted to low oxygen environments, but the mechanisms by which their growth in air is inhibited are not well understood. The citric acid cycle in the microaerophilic pathogen C ampylobacter jejuni is potentially vulnerable, as it employs pyruvate and 2‐oxoglutarate:acceptor oxidoreductases ( P or and O or), which contain labile (4 Fe ‐4 S ) centres. Here, we show that both enzymes are rapidly inactivated after exposure of cells to a fully aerobic environment. We investigated the mechanisms that might protect enzyme activity and identify a role for the hemerythrin HerA (Cj0241). A herA mutant exhibits an aerobic growth defect and reduced P or and O or activities after exposure to 21% (v/v) oxygen. Slow anaerobic recovery of these activities after oxygen damage was observed, but at similar rates in both wild‐type and herA strains, suggesting the role of HerA is to prevent Fe ‐ S cluster damage, rather than promote repair. Another hemerythrin ( HerB ; Cj1224) also plays a protective role. Purified HerA and HerB exhibited optical absorption, ligand binding and resonance R aman spectra typical of μ‐oxo‐bridged di‐iron containing hemerythrins. We conclude that oxygen lability and poor repair of P or and O or are major contributors to microaerophily in C . jejuni ; hemerythrins help prevent enzyme damage microaerobically or during oxygen transients.