Journal
BIOMETALS
Volume 33, Issue 4-5, Pages 187-200Publisher
SPRINGER
DOI: 10.1007/s10534-020-00241-5
Keywords
Clinical isolate; Siderophore-interacting protein; Ferric-siderophore reductase; Vulnibactin; Aerobactin; Desferrioxamine B
Categories
Funding
- Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan [S1101031]
Ask authors/readers for more resources
Vibrio vulnificus, a pathogenic bacterium that causes serious infections in humans, requires iron for growth. Clinical isolate,V. vulnificusM2799, secretes a catecholate siderophore, namely, vulnibactin, to capture iron (III) from the environment. Growth experiments using a deletion mutant indicated that VuuB, a member of the FAD-containing siderophore-interacting protein family, plays a crucial role in Fe3+-vulnibactin reduction. IutB, a member of the ferric-siderophore reductase family, stands a substitute for VuuB in its absence. It remained unclear whyV. vulnificusM2799 has two proteins with relevant functions. Here we biochemically characterized VuuB and IutB using purified recombinant proteins. Purified VuuB, a flavoprotein, catalyzed the reduction of Fe3+-nitrilotriacetic acid as its electron acceptor, in the presence of NADH as its electron donor and FAD as its cofactor. IutB catalyzed the reduction of Fe3+-nitrilotriacetic acid, in the presence of NADH, NADPH, or reduced glutathione as its electron donor. The optimal pH values and temperatures of VuuB and IutB were 7.0 and 37 degrees C, and 8.5 and 45 degrees C, respectively. On analyzing their ferric-chelate reductase activities, both VuuB and IutB were found to catalyze the reduction of Fe3+-aerobactin, Fe3+-vibriobactin, and Fe3+-vulnibactin. When the biologically relevant substrate, Fe3+-vulnibactin, was used, the levels of ferric-chelate reductase activities were similar between VuuB and IutB. Finally, the mRNA levels were quantified by qRT-PCR in M2799 cells cultivated under low-iron conditions. The number ofvuuBmRNA was 8.5 times greater than that ofiutB. The expression ratio correlated with the growth of their mutants in the presence of vulnibactin.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available