Latest revision as of 10:25, 19 October 2021

Anoxyc Respiratory Control system

This system is composed by the response regulator ArcA and the sense kinase ArcB. When E. coli is under Anaerobic conditions ArcB has kinase activity, so it phosphorylate ArcA protein which is activated and repress the gene related with aerobic metabolism.

Biology

ArcA (aerobic respiratory control), a global regulator important for E. coli's adaptation from anaerobic to aerobic conditions and control of that bacterium's enzymatic defenses against reactive oxygen species (ROS). ArcA played a dual role in the control of citrate metabolism and transportation.

Additional information on old part learnt from literature (Team: Hong_Kong_UCCKE 2021)

We have learnt the following from this study: Effect of iclR and arcA knockouts on biomass formation and metabolic fluxes in Escherichia coli K12 and its implications on understanding the metabolism of Escherichia coli BL21 (DE3).

In theis study, experiments were done on the three strains, which are the single knockouts arcA- and iclR- and the double knockout arcA-iclR-. The three strains are produced from K12 MG1655. The knockout strains were compared against the BL21 DE3 strain in terms of their metabolic flux, especially the flux of carbon molecules through different pathways.

ArcA is a protein that regulates genes that take part in various metabolic pathways as a global regulator, while IclR is a protein that controls the transcription of the glyoxylate pathway under the aceBAK operon as a local regulator.

iclR- and arcA- had a maximum growth rate reduction of up to 13%, while arcA-iclR- exhibits a reduction as much as 38% compared to wild-type parent E. coli in batch culture conditions, where glucose is abundant and limited.

arcA-iclR- exhibits an increased biomass yield of 0.63 c-mole/c-mole glucose under glucose abundant conditions, with the maximum theoretical yield of about 0.65 c-mole/c-mole glucose. There also is an observed decrease in acetate formation and CO2 production. There is an increase in the transcription of glyoxylate enzymes, meaning that the pathway is activated despite the absence of crp-activation under glucose limiting conditions. Moreover, the transcription of TCA genes are liberated in arcA- which causes a higher flux in the TCA cycle, causing lower acetate formation. Flux in the glyoxylate pathway is further increased in iclR- under glucose limiting conditions, but this effect was not observed in arcA-iclR-.

References

H. Waegeman, J. Beauprez, H. Moens, J. Maertens, M. De Mey, M. R. Foulquié-Moreno, J. J. Heijnen, D. Charlier, and W. Soetaert, “Effect of ICLR and ARCA knockouts on biomass formation and metabolic fluxes in escherichia coli K12 and its implications on understanding the metabolism of escherichia coli BL21 (DE3),” BMC Microbiology, vol. 11, no. 1, p. 70, 2011.

Sequence and Features