Mutations in the flhD gene of Escherichia coli K-12 do not cause the reported effect on cell division.

The hetero-oligomeric FlhD/FlhC complex is a global regulator of transcription in Escherichia coli. FlhD alone, independent of FlhC, has also been reported to control when E. coli cells stop dividing and enter the stationary phase. This work is frequently cited as evidence that FlhD regulates cell division; however, our data indicate that this is not the case. The results presented here show that the previously observed phenotype is not due to the flhD locus, but is instead due to differences in the thyA alleles present in the flhD(+) and flhD(-) strains used in the original studies. We find that when the strains being compared have the same thyA allele (wild type or mutant), flhD mutations have no effect on growth.