Abstract
One of the pathways involved in the acquisition of the essential metal iron by bacteria involves the reduction of insoluble Fe(3+) to soluble Fe(2+), followed by transport of Fe(2+) to the cytoplasm. Flavins have been implicated as electron donors in this poorly understood process. Ferrous iron uptake is essential for intestinal colonization by the important pathogen Campylobacter jejuni and may be of particular importance under low-oxygen conditions. In this study, the links among riboflavin biosynthesis, ferric reduction, and iron acquisition in C. jejuni NCTC11168 have been investigated. A riboflavin auxotroph was generated by inactivation of the ribB riboflavin biosynthesis gene (Cj0572), and the resulting isogenic ribB mutant only grew in the presence of exogenous riboflavin or the riboflavin precursor diacetyl but not in the presence of the downstream products flavin adenine dinucleotide and flavin mononucleotide. Riboflavin uptake was unaffected in the ribB mutant under iron-limited conditions but was lower in both the wild-type strain and the ribB mutant under iron-replete conditions. Mutation of the fur gene, which encodes an iron uptake regulator of C. jejuni, resulted in an increase in riboflavin uptake which was independent of the iron content of the medium, suggesting a role for Fur in the regulation of the as-yet-unknown riboflavin transport system. Finally, ferric reduction activity was independent of iron availability in the growth medium but was lowered in the ribB mutant compared to the wild-type strain and, conversely, increased in the fur mutant. Taken together, the findings confirm close relationships among iron acquisition, riboflavin production, and riboflavin uptake in C. jejuni.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.