Regulation of iron-siderophore uptake in a diazotrophic cyanobacterium Anabaena anabaena 7120

Abstract

The regulation of 55Fe-siderophore uptake of was studied in a diazotrophic cyanobacterium Anabaena 7120. The uptake up to 20 min was found to be biphasic, a rapid first and steady second phase. A single kinetic system mediated the uptake of iron-siderophore with an apparent Km of 200 µM and a Vmax of 20 nmol iron taken up mg-1 protein min-1. 3-(3,4dichlorophenyl)-1, 1-dimethyl urea (DCMU), 2-n-heptyl-4-hydroxy quinoline (HOQNO), dicyclohexyl carbodiimide (DCCD), carbonyl cyanide p-fluoromethoxy phenyl hydrazone (FCCP) and carbonyl cyanide-m-chlorophenyl hydrazone (CCCP) inhibited the iron-siderophore uptake significantly, whereas KCN inhibited marginally. No iron-siderophore uptake was observed under dark-aerobic and dark-anaerobic conditions. The siderophore schizokinen supported the maximum iron-siderophore uptake. However, the siderophore aerobactin and desferal could support only 53 and 3.4% iron-siderophore uptake, respectively as compared to its schizokinen counterpart.