Characterization of the ftsZ cell division gene of Neisseria gonorrhoeae: expression in Escherichia coli and N. gonorrhoeae

Abstract

We cloned the cell division gene ftsZ of the gram-negative coccus Neisseria gonorrhoeae (Ng) strain CH811, characterized it genetically and phenotypically, and studied its localization in N. gonorrhoeae and Escherichia coli (Ec). The 1,179-bp ORF of ftsZ _Ng encodes a protein with a predicted molecular mass of 41.5 kDa. Protein sequence alignments indicate that FtsZ_Ng is similar to other FtsZ proteins and contains the conserved GTP binding motif. FtsZ homologues were identified in several N. gonorrhoeae strains and in Neisseria lactamica, Neisseria sicca, Neisseria polysaccharae and Neisseria cinerea either by Western blot or by PCR-Southern blot analysis. Attempts to inactivate the ftsZ _Ng on the chromosome failed, indicating that it is essential for gonococcal growth. FtsZ_Ng was synthesized in an in vitro transcription/translation system and was shown to be 43 kDa, the same size as in Western blots. Expression of the ftsZ _Ng gene from nongonococcal promoters resulted in a filamentous phenotype in E. coli. Under controlled expression, the FtsZ_Ng-GFP fusion protein localized at the mid-cell division site in E. coli. E. coli expressing high levels of the FtsZ_Ng-GFP fusion protein formed filaments and exhibited different fluorescent structures including helices, spiral tubules extending from pole to pole, and regularly spaced dots or bands that did not localize ¶at the middle of the cell. Expression of the FtsZ_Ng-GFP fusion protein in N. gonorrhoeae resulted in abnormal cell division as shown by electron microscopy. FtsZ_Ng-GFP fusions were also expressed in a gonococcal background using a unique shuttle vector.