| Abstract
| - Bacterial diseases are among the leading causes of human death. The development of antibioticresistance greatly contributes to the high mortality rate, and thus, the discovery of antibacterial drugswith novel mechanisms of action is needed. In this study, we found that sanguinarine, a benzophenanthridinealkaloid, strongly induced filamentation in both Gram-positive and Gram-negative bacteria and preventedbacterial cell division by inhibiting cytokinesis. Sanguinarine did not perturb the membrane structure inEscherichia coli. However, it perturbed the cytokinetic Z-ring formation in E. coli. In addition, sanguinarinestrongly reduced the frequency of the occurrence of Z rings/micrometer of Bacillus subtilis length but didnot alter the number of nucleoids/micrometer of cell length. The results suggested that sanguinarine inhibitedcytokinesis in B. subtilis by inhibiting Z-ring formation without affecting nucleoid segregation. Sanguinarineinhibited the assembly of purified FtsZ and reduced the bundling of FtsZ protofilaments in vitro. Further,the interaction of sanguinarine to FtsZ was investigated using size-exclusion chromatography, an extrinsicfluorescent probe 1-anilinonaphthalene-8-sulfonic acid, and tryptophan fluorescence of mutated FtsZ(Y371W). Sanguinarine was found to bind to FtsZ with a dissociation constant of 18−30 μM. The resultstogether show that sanguinarine inhibits bacterial division by perturbing FtsZ assembly dynamics in theZ ring and provide evidence in support of the hypothesis that the assembly and bundling of FtsZ play acritical role in bacterial cytokinesis. The results suggest that sanguinarine may be used as a lead compoundto develop FtsZ-targeted antibacterial agents.
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