title: A mixed incoherent feed-forward loop allows conditional regulation of response dynamics.
abstract: Expression of the SodA superoxide dismutase (MnSOD) in Escherichia coli is regulated by superoxide concentration through the SoxRS system and also by Fur (Ferric uptake regulator) through a mixed incoherent feed forward loop (FFL) containing the RyhB small regulatory RNA. In this work I theoretically analyze the function of this feed forward loop as part of the network controlling expression of the two cytoplasmic superoxide dismutases, SodA and SodB. I find that feed forward regulation allows faster response to superoxide stress at low intracellular iron levels compared to iron rich conditions. That is, it can conditionally modulate the response time of a superimposed transcriptional control mechanism.
authors.affiliation: Center for Models of Life, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Szabolcs
authors.initials: S
authors.lastname: Semsey
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D025461:Feedback, Physiological; D015964:Gene Expression Regulation, Bacterial; D007501:Iron / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics* / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D012333:RNA, Messenger; D013481:Superoxides; D007501:Iron; C095500:SodA protein, Bacteria; C087504:SodB protein, Bacteria; D013482:Superoxide Dismutase