Involvement of the ftsA gene product in late stages of the Escherichia coli cell cycle.

Strain D-3 was shown, by genetic complementation with lambda phage vectors carrying either the wild type or a temperature-sensitive allele, to contain an ftsA mutation. The presence of this mutation rendered the strain unable to divide at 42 degrees C. The action of the ftsA gene product in strain D-3 takes place at a late stage of the cycle, starting near the end of the replication cycle and extending until cell division is completed. The action of the ftsA gene product seemed to take a constant time, independent of the duration of the cell division cycle. Experiments in which all other requirements for division except a "termination protein" were completed show that cells of strain D-3 can divide under these conditions only at the permissive temperature. We conclude that a likely role for the ftsA gene product is that of a termination protein.