 |
PDBsum entry 1te0
|
|
|
|
References listed in PDB file
|
 |
|
Key reference
|
|
|
Title
|
|
Structural analysis of degs, A stress sensor of the bacterial periplasm.
|
|
|
Author
|
|
K.Zeth.
|
|
|
Ref.
|
|
FEBS Lett, 2004,
569,
351-358.
[DOI no: ]
|
|
|
PubMed id
|
|
|
|
|
|
Abstract
|
|
|
Regulated proteolysis is a key event in transmembrane signalling between
intracellular compartments. In Escherichia coli the membrane-bound protease DegS
has been identified as the periplasmic stress sensor for unfolded outer membrane
proteins (OMPs). DegS inititates a proteolytic cascade resulting in the release
of sigmaE the transcription factor of periplasmic genes. The crystal structure
of DegS protease reported at 2.2 A resolution reveals a trimeric complex with
the monomeric protease domain in an inhibited state followed by the inhibitory
PDZ domain. Noteably, domain architecture and communication of DegS are
remarkably to homologous proteins known to date. Here the domain interface is
mechanically locked by three intradomain salt bridges. Co-crystallisation trials
in the presence of a 10-residue activating peptide did not result in significant
structural intradomain shifts nor distortions in the crystal packing. These
observations imply a mode of activation indicative of peptide-induced structural
shifts imposed to the protease domain rather than disturbing the PDZ-protease
interface.
|
|
|
|
|
|
|
|
Figure 1.
Fig. 1. Crystal structure of the substrate sensor DegS from
E. coli. (a) Schematic representation of DegS structure showing
the protease domain in brown and the PDZ domain in blue. N- and
C-termini (NT, CT), the β-strands (β1–β18), α-helices
(α1–α9) and loop structures (L1–L6) important for the
function are indicated. Residues of the catalytic triade and the
domain interface are highlighted and marked by dotted circles.
(b) Close-up of the 2|F[obs]−F[calc]| electron density map
calculated around the protease active center and contoured at
1.2σ. The residues forming the catalytic triade (His96, Asp126
and Ser201) are marked. (c) A close-up view of the
intramolecular hydrophilic contacts between protease (brown) and
PDZ (blue) domain. Important residues of the interface are
marked with numbers according to the DegS sequence.
|
|
Figure 3.
Fig. 3. Structural comparison of Htra proteins. (a)
Structural alignment of the protease backbone atoms. N- and
C-termini (NT, CT), loop5 (L5) and resdiues of the catalytic
triade are assigned in ball and stick for clarity. The following
colour code was used: DegS is magenta, DegP is cyan and
HtrA2/Omi is coloured in blue. (b) Structural alignment of the
PDZ domain with the same colour code used in (a). Selected
secondary structure elements are marked. (c) Overlay of the
active site residues from DegS, DegP, HtrA2/Omi and trypsin
(in green). Residue numbers are assigned with respect to the
DegS sequence. (d) Crystal structure of DegP with the protease
domain superimposed onto DegS and the domain colour code
according to the DegS structure in Fig. 1(a). (e) Crystal
structure of HtrA2/Omi with the protease domain structurally
aligned to DegS and the same colour code as for figure (d).
|
|
|
|
|
|
The above figures are
reprinted
by permission from the Federation of European Biochemical Societies:
FEBS Lett
(2004,
569,
351-358)
copyright 2004.
|
|
|
|
|
|
|
