ArcA-Mediated Regulation Of The Escherichia Coli Cell Cycle

The Escherichia coli ArcB/ArcA two-component system is important signaling system, responding to anaerobic condition. However, we found that ArcA also affects cell cycle under aerobic condition.The study found that mutant of the arcA gene delayed initiation of DNA replication, decreased cell size and growth rate in LB medium; the mutant of arcA led to an early initiation of replication and larger cells in ABTGcasa medium. The results indicate that the effects of ArcA on initiation of replication and cell division depend on nutrition. Interestingly, mutant of the arcB gene also affected initiation of replication in the manner of ArcA-mediated effects, suggesting that the ArcB/ArcA signal pathway affects initiation of replication. Western blot analysis showed that mutant of arcA led to a decrease in DnaA amount per cell grown in LB while an increase in ABTGcasa medium. Further, external addition of cysteine reversed the changes in initiation of replication caused by the mutant of arcA in mode of nutrition-dependent. It was found that ArcA-GFP colocalized with chromosomal DNA in LB medium while did not in ABTGcasa medium.We concluded that ArcA affects initiation of DNA replication by changing amount of DnaA per cell, the effect depends on nutrition.