Fig. (3).

Regulation of iron metabolism in MTB (A). Under iron deprived condition the regulator IdeR cannot bind to the iron box in the promotor region as it requires iron for its activation. Thus the genes (iron storage) which are positively regulated by IdeR are not transcribed whereas the genes (siderophore) which are negatively regulated by IdeR are actively transcribed. (B). Under iron rich condition the regulator IdeR can bind to the iron box in the promotor region hence in active form. Thus the genes (iron storage) which are positively regulated by IdeR are actively transcribed whereas the genes (siderophore) which are negatively regulated by IdeR are not transcribed.