Characterization and in vitro inhibition studies of Bacillus anthracis FtsZ: a potential antibacterial target

FtsZ is an essential bacterial cell division protein that is an attractive target for the development of antibacterial agents. FtsZ is a homologue of eukaryotic tubulin, has GTPase activity, and forms a ring-type structure to initiate cell division. In this study, the FtsZ of Bacillus anthracis was cloned into a bacterial expression vector and overexpressed into Escherichia coli BL21 (DE3) cells. The overexpressed B. anthracis FtsZ was soluble and purified to homogeneity using Ni-His-tag affinity chromatography. Like other known FtsZs, the recombinant B. anthracis FtsZ also showed GTP-dependent polymerization, which was analyzed using both spectrophotometric and Transmission Electronic Microscopic (TEM) analysis. Using the purified FtsZ, we screened a naturally extracted chemical library to identify potent and novel inhibitors. The screening yielded three chemicals, SA-011, SA-059, and SA-069, that inhibited the in vitro polymerization activity of FtsZ in the micromolar range (IC50 of 55-168 μM). The inhibition potency was significantly comparable with that of berberine, a known potential inhibitor of FtsZ. Understanding the biochemical basis of the effect of these inhibitors on B. anthracis growth would provide a promising path for the development of new antianthracis drugs.