Borrelia burgdorferi ftsZ Plays a Role in Cell Division

Abstract

ABSTRACT ftsZ is essential for cell division in many microorganisms. In Escherichia coli and Bacillus subtilis , FtsZ plays a role in ring formation at the leading edge of the cell division septum. An ftsZ homologue is present in the Borrelia burgdorferi genome ( ftsZ Bbu ). Its gene product (FtsZ Bbu ) is strongly homologous to other bacterial FtsZ proteins, but its function has not been established. Because loss-of-function mutants of ftsZ Bbu might be lethal, the tetR/tetO system was adapted for regulated control of this gene in B. burgdorferi . Sixty-two nucleotides of an ftsZ Bbu antisense DNA sequence under the control of a tetracycline-responsive modified hybrid borrelial promoter were cloned into pKFSS1. This construct was electroporated into a B. burgdorferi host strain carrying a chromosomally located tetR under the control of the B. burgdorferi flaB promoter. After induction by anhydrotetracycline, expression of antisense ftsZ RNA resulted in generation of filamentous B. burgdorferi that were unable to divide and grew more slowly than uninduced cells. To determine whether FtsZ Bbu could interfere with the function of E. coli FtsZ, ftsZ Bbu was amplified from chromosomal DNA and placed under the control of the tetracycline-regulated hybrid promoter. After introduction of the construct into E. coli and induction with anhydrotetracycline, overexpression of ftsZ Bbu generated a filamentous phenotype. This suggested interference of ftsZ Bbu with E. coli FtsZ function and confirmed the role of ftsZ Bbu in cell division. This is the first report of the generation of a B. burgdorferi conditional lethal mutant equivalent by tetracycline-controlled expression of antisense RNA.