The same behavior has been described for other ArcA-controlled promoters in 6 Time : 14:6 # lpxO Expression Is Regulated by Fnr and ArcA in Response to Oxygen Availability FIGURE 2  Main lipid-A species produced by S. Enteritidis .
genetic analyses indicate that this process is regulated by ArcA controlling the expression of lpxO .
Biochemical analyses indicate that this process is regulated by ArcA controlling the expression of lpxO .
The above results led us to hypothesize that lpxO expression is regulated by oxygen availability through the activity of transcription regulators ArcA and/or Fnr .
These observations suggest that ArcA is a negative regulator of lpxO expression under anaerobic conditions .
On the other hand , both ArcA bound to the lpxO promoter .
These results indicate that ArcA regulate lpxO expression through direct binding to its promoter region .
In addition , we also demonstrate that ArcA control the oxygen-dependent lipid-A hydroxylation by directly regulating the expression of lpxO .
Our results also showed that both ArcA are able to bind in-vitro to the promoter regions of lpxO , strongly suggesting a direct role for these regulators in the control of lpxO transcription .
Our results also showed that both ArcA are able to bind in-vitro to the promoter regions of lpxO , strongly suggesting a direct role for these regulators in the control of lpxO transcription .
a model in which ArcA control the expression of lpxO in S. Enteritidis to achieve a fine-tuning of lipid-A hydroxylation levels