The Structure of RseB, a Sensor for Periplasmic Stress in Escherichia coli

RseB from Escherichia coli has been crystallized and crystal
structures were determined at 2.4 Å and at 2.8 Å resolution. The
structure of cytoplasmic expressed RseB revealed that it consists
of two domains; an N-terminal large and a C-terminal small domain.
The large domain resembles an unclosed β-barrel that is
structurally remarkably similar to a protein family (LolA, LolB)
capable of binding the lipid anchor of lipoproteins. Detailed
structural comparison of RseB and LolA led to the hypothesis that
RseB might be a sensor for mislocalized lipoproteins. The small
C-terminal domain, connected to the large domain by a partially
unstructured loop, was identified to mediate interaction with RseA.
A peptide comprised of a putative helix of RseA was shown to
constitute the binding site for RseB. Structure based results
presented in this thesis indicate a new role of RseB in acting as a
sensor for periplasmic stress: it detects mislocalized lipoproteins
in the periplasm and propagates the signal to induce σE-response.