Hemerythrins in the microaerophilic bacterium Campylobacter jejuni help protect key iron–sulphur cluster enzymes from oxidative damage. (17th December 2013)

• Record Type: Journal Article
• Authors: Kendall, John J.; Barrero‐Tobon, Angelica M.; Hendrixson, David R.; Kelly, David J.
• Is Part Of: Environmental microbiology. Volume 16:Number 4(2014:Apr.)
• Page Start: 1105
• Page End: 1121
• Publication Date: 2013-12-17
• Subjects: Microbial ecology -- Periodicals; Environmental Microbiology -- Periodicals; 579.17
• DOI: 10.1111/1462-2920.12341
• Languages: English
• ISSNs: 1462-2912

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>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 <italic>C</italic><italic>ampylobacter jejuni</italic> is potentially vulnerable, as it employs pyruvate and 2‐oxoglutarate:acceptor oxidoreductases (Por and Oor), which contain labile (4Fe‐4S) 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 <italic>herA</italic> mutant exhibits an aerobic growth defect and reduced Por and Oor 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 <italic>herA</italic> 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 Raman spectra typical of μ‐oxo‐bridged di‐iron containing hemerythrins. We conclude that oxygen lability and poor repair of Por and Oor are major contributors to microaerophily in <italic>C</italic><italic>. jejuni</italic>; hemerythrins help prevent enzyme damage microaerobically or during oxygen transients.</p> </abstract>