Negatively modulates the activity of sigma-E (RpoE) by stabilizing RseA under non-stress conditions. Although not essential for association of sigma-E with Rsea it increases their affinity 2- to 3-fold. When bound to RseA it prevents proteolysis by DegS, which is probably relieved by lipopolysaccharide binding (LPS) (By similarity). Binding to RseA is inhibited by LPS fragments; phosphorylated N-acetylglucosamine (GlcNAc) with N-linked acyl chains are minimally necessary to disrupt binding to RseA. Once RseB is no longer bound to RseA the latter is susceptible to DegS degradation. Thus if periplasmic LPS levels increase the sigma-E regulon is induced (By similarity). Homodimer. Interacts with RseA (By similarity). Partially associates with the inner membrane via RseA. Belongs to the RseB family.