Construction of a ferritin-deficient mutant of Campylobacter jejuni: contribution of ferritin to iron storage and protection against oxidative stress

The ferritin-encoding gene (cft) of Campylobacter jejuni was cloned and sequenced. The nucleotide sequence of cft had a 501 bp open reading frame for a protein with 167 amino acids and a predicted molecular mass of 19180 Da, and showed a high similarity to that of Helicobacter pylori and Escherichia coli ferritin genes. To determine the biological function of ferritin in C. jejuni, a ferritin-deficient mutant was constructed. The growth of ferritin-deficient strain SNA1 was clearly inhibited under iron deprivation. The ferritin-deficient mutant was more sensitive to killing by H₂O₂ and paraquat than the isogenic parent strain. These findings demonstrate that ferritin in C. jejuni makes a significant contribution to both iron storage and protection from intracellular iron overload, and resulting iron-mediated oxidative stress.