PDBsum entry 2cea

Hydrolase

PDB id: 2cea

Contents

Protein chains

(+ 0 more) 407 a.a.

Ligands

ADP ×6

Metals

_MG ×6

_ZN ×6

Waters ×199

References listed in PDB file

Key reference

Title

The molecular architecture of the metalloprotease ftsh.

Authors

C.Bieniossek, T.Schalch, M.Bumann, M.Meister, R.Meier, U.Baumann.

Ref.

Proc Natl Acad Sci U S A, 2006, 103, 3066-3071. [DOI no: 10.1073/pnas.0600031103]

PubMed id

16484367

Abstract

The ATP-dependent integral membrane protease FtsH is universally conserved in bacteria. Orthologs exist in chloroplasts and mitochondria, where in humans the loss of a close FtsH-homolog causes a form of spastic paraplegia. FtsH plays a crucial role in quality control by degrading unneeded or damaged membrane proteins, but it also targets soluble signaling factors like sigma(32) and lambda-CII. We report here the crystal structure of a soluble FtsH construct that is functional in caseinolytic and ATPase assays. The molecular architecture of this hexameric molecule consists of two rings where the protease domains possess an all-helical fold and form a flat hexagon that is covered by a toroid built by the AAA domains. The active site of the protease classifies FtsH as an Asp-zincin, contrary to a previous report. The different symmetries of protease and AAA rings suggest a possible translocation mechanism of the target polypeptide chain into the interior of the molecule where the proteolytic sites are located.

Figure 2.
Fig. 2. The hexameric structure of FtsH. (A) Top view approximately down the crystallographic twofold axis from the supposed membrane side onto the AAA ring. The colors denote the individual subunits. ADP and active site residues are shown as sticks (gray, carbons; blue, nitrogens; red, oxygens; cyan, phosphorous), and the Zn^2+ ions are shown as golden spheres. (B) Side view, the AAA ring is on the bottom, the protease ring on the top.

Figure 4.
Fig. 4. Surface representation. (A) Top view onto AAA ring. Phe-234 residues are colored in yellow and magenta, and Arg-318 is in orange. The orientation is the same as in Fig. 2A. ADP residues are shown as sticks. Subunits are shaded alternately light and dark. (B) Modeled ideal hexameric arrangement of the AAA domains. The protease ring is in the same orientation as in A and Fig. 2A.