Fig 9.

Model of the QseC and QseE regulatory cascade. Solid lines with arrows indicate confirmed positive interactions, while dotted lines indicate indirect or unconfirmed direct interactions. QseC phosphorylates QseB, which directly activates transcription of flhDC to promote expression of flagella. Through phosphorylation of KdpE, QseC activates expression of the LEE genes. QseF is phosphorylated by both QseC and QseE. QseF indirectly activates expression of espFu and Shiga toxin. QseE inhibits rcsB transcription in an as yet undetermined manner. Given that RcsB activates expression of the LEE and nleA, QseE inhibition of rcsB inhibits LEE and nleA expression. How QseC influences nleA expression is unknown. epi, epinephrine; NE, norepinephrine; AE, attaching and effacing; HUS, hemolytic-uremic syndrome.