Iron acquisition is essential for growth of Mycobacterium tuberculosis, but most iron in the human body is tightly bound to proteins. To obtain iron M. tuberculosis secretes small molecules with high iron affinity, the siderophores mycobactin (MBT) and carboxy-MBT (cMBT), and takes up iron-loaded siderophores. M. tuberculosis also utilizes heme and hemoglobin as iron sources. We discovered a novel siderophore secretion system and showed that M. tuberculosis recycles its secreted siderophores to efficiently acquire extracellular iron. The capability of M. tuberculosis to utilize heme and hemoglobin as iron sources is probably even more important considering that more than 70% of the iron in the human body is in heme. Recently, we have identified novel cell surface proteins and an inner membrane uptake system that are required for heme utilization by M. tuberculosis. These discoveries show that both siderophore- and heme-based iron acquisition mechanisms of M. tuberculosis are very different compared to other bacteria.
Host: Prof. Amit R Reddi firstname.lastname@example.org