Negative regulatory role of the Escherichia coli hfq gene in cell division.

We found that the hfq::cat mutant strain produced minicells at high frequency. Minicell production by the mutant strain was more prominent in poor media and in the stationary phase than in rich media and in the exponentially growing phase. The amount of the cell division protein FtsZ increased up to two- to threefold of the wild-type cells in the hfq::cat mutant in the stationary phase, while such differences were not observed in the exponentially growing phase. Increased ftsZ mRNA levels were also observed in the hfq::cat mutant in the stationary phase. These results suggest a negative regulatory role of the DNA-, RNA-binding protein Hfq in cell division in the stationary phase.