Rsbr is a regulator of the RNA polymerase sigma factor subunit sigma(B). The structure of the N terminal domain belongs to the globin fold superfamily [1].

1: Structure of a nonheme globin in environmental stress signaling. Murray JW, Delumeau O, Lewis RJ; Proc Natl Acad Sci U S A. 2005;102:17320-17325. PMID:16301540