Fig. 1.

The crystal structure of EcUppP at 2.0 Å resolution. a Cartoon representation of EcUppP dimer with one monomer-colored rainbow from the N- (blue) to C-terminal (red). Aromatic and positively charged residues at the membrane interface shown as stick and highlight orientation with respect to the inner membrane (shown as gray bars). Two monoolein lipids at the dimer interface shown as stick. b Ninety-degree rotation from a viewed from periplasm. Colored as a and helices numbered. Twofold pseudosymmetry axis parallel to the plane of the membrane shown as gray dotted line. c Electrostatic surface potential of UppP monomer. Orientations as in a and b, respectively. Dotted circles indicate location of periplasmic substrate-binding cleft. d Secondary structure topology highlighting interlocked inverted repeat