The iron-induced ferredoxin FdxA of Campylobacter jejuni is involved in aerotolerance

A gene encoding a putative 2[4Fe-4S] ferredoxin (FdxA) was identified upstr eam of, and divergent to the peroxide stress defense gene ahpC of the micro aerophilic pathogen Campylobacter jejuni. The transcription start site of f dxA was located 27 and 28 bp upstream of the fdxA start codon. Transcriptio nal fusions of the fdxA promoter to a lacZ reporter gene demonstrated that expression of fdxA is iron-induced, and thus oppositely regulated to the ir on-repressed ahpC gene. Insertional mutagenesis of the fdxA gene did not af fect microaerobic growth of C. jejuni, but significantly reduced aerotolera nce of C. jejuni. The fdxA gene is the first reported iron-induced gene of C. jejuni, and encodes a novel component of its oxidative stress defense. ( C) 2001 Federation of European Microbiological Societies. Published by Else vier Science B.V. All rights reserved.