Deletion of the cell-division inhibitor MinC results in lysis of Neisseriagonorrhoeae

The minCDE genes involved in division site selection in Neisseria gonorrhoe ae were identified using raw data from the N. gonorrhoeae genome project an d are part of a cluster of 27 genes. When gonococcal min genes were heterol ogously expressed as a cluster in Escherichia coil, minicells and filaments were produced, indicating that gonococcal min genes disrupted cell divisio n in other genera. The insertional inactivation of the minC gene of N. gono rrhoeae CH811 resulted in a strain (CSRC1) with decreased viability and gro ssly abnormal cell division as observed by phase-contrast and electron micr oscopy analysis. Western blot analysis of N. gonorrhoeae CSRC1 confirmed th at MinC(Ng) was not produced. Complementation of CSRC1 by integrating a min C-6 x His tag fusion at the proAB locus by homologous recombination restore d viability and 1.9 times wild-type revels of MinC(Ng) expression. This sli ght increase of expression caused a small percentage of the complemented ce lls to divide aberrantly. This suggested that the 6 x His tag has partially affected the stability of MinC, or that the chromosomal position of minC i s critical to its regulation. Comparison of MinC proteins from different ba cteria showed a homologous region corresponding to residues 135-230 with fi ve conserved amino acids. Overexpression of MinC(Ng) in wild-type E. coil c ells induced filamentation and an E. coil minC mutant was successfully comp lemented with minC(Ng). Therefore, the evidence indicates that MinC from N. gonorrhoeae acts as a cell-division inhibitor and that its role is essenti al in maintaining proper division in cocci.