MUTATIONS IN CELL-DIVISION PROTEINS FTSZ AND FTSA INHIBIT PHI-X174 PROTEIN-E-MEDIATED LYSIS OF ESCHERICHIA-COLI

Electron microscopic studies emphasized that the protein-E-specific tr ansmembrane tunnel structure, which permeabilizes Escherichia coli, is not randomly distributed over the cell envelope but is restricted to areas of potential division sites. These sites were located predominan tly in the middle of the cell, but approximately one-third of these st ructures are found at the polar sites. Therefore, E. coli mutant strai ns with defects in cell division components were tested for their sens itivity to protein-E-mediated lysis. The ftsZ84 and the ftsA12 cell di vision mutant strains of E. coli were tolerant to protein-E-mediated l ysis, whereas the ftsA3 mutant strain was lysed by protein E under con ditions nonpermissive for division. The protein-E-tolerant phenotype o f ftsZ84 and ftsA12 and the lysis-sensitive phenotype of other compone nts of the septosome (e.g.,ftsA3, ftsQ, and ftsl) suggest that initiat ion of cell division - rather than specific functions of cell division - plays an essential role in protein-E-mediated lysis. SulA-overprodu cing cells had a lysis-positive phenotype, the ring structure - but no t the GTPase function - of FtsZ was impaired.