FIG. 7.

Current model that displays the role of RpoE, RpoH_I and RpoH_II in the response to ¹O₂ and heat stress in R. sphaeroides. Solid black arrows indicate strong positive effects in the regulatory cascade triggered by ¹O₂ and heat stress. Solid gray arrows indicate less pronounced positive effects in the regulatory cascade. Dashed arrows indicate the function of hypothetical expression factors involved in the RpoE-RpoH_II-dependent gene induction. Representative promoter sequences for RpoE (2, 11) and the putative promoter consensus sequences for RpoH_II or rather RpoH_I/RpoH_II (Fig. 4B) are depicted. K: T or G; Y: T or C; B: T, C, or G; V: A, C, or G; M: C or A.