3BEZ

Crystal structure of Escherichia coli Signal peptide peptidase (SppA), SeMet crystals

Summary for 3BEZ

• Entry DOI: 10.2210/pdb3bez/pdb
• Related: 3BF0
• Descriptor: Protease 4 (2 entities in total)
• Functional Keywords: protease, bacterial, hydrolase, inner membrane, membrane, transmembrane
• Biological source: Escherichia coli
• Cellular location: Cell inner membrane ; Single- pass membrane protein : P08395
• Total number of polymer chains: 4
• Total formula weight: 258492.41

Authors

Paetzel, M. (deposition date: 2007-11-20, release date: 2007-12-18, Last modification date: 2024-11-20)

Primary citation

Kim, A.C.,Oliver, D.C.,Paetzel, M.
Crystal structure of a bacterial signal Peptide peptidase.
J.Mol.Biol., 376:352-366, 2008

PubMed Abstract: Signal peptide peptidase (Spp) is the enzyme responsible for cleaving the remnant signal peptides left behind in the membrane following Sec-dependent protein secretion. Spp activity appears to be present in all cell types, eukaryotic, prokaryotic and archaeal. Here we report the first structure of a signal peptide peptidase, that of the Escherichia coli SppA (SppA(EC)). SppA(EC) forms a tetrameric assembly with a novel bowl-shaped architecture. The bowl has a dramatically hydrophobic interior and contains four separate active sites that utilize a Ser/Lys catalytic dyad mechanism. Our structural analysis of SppA reveals that while in many Gram-negative bacteria as well as characterized plant variants, a tandem duplication in the protein fold creates an intact active site at the interface between the repeated domains, other species, particularly Gram-positive and archaeal organisms, encode half-size, unduplicated SppA variants that could form similar oligomers to their duplicated counterparts, but using an octamer arrangement and with the catalytic residues provided by neighboring monomers. The structure reveals a similarity in the protein fold between the domains in the periplasmic Ser/Lys protease SppA and the monomers seen in the cytoplasmic Ser/His/Asp protease ClpP. We propose that SppA may, in addition to its role in signal peptide hydrolysis, have a role in the quality assurance of periplasmic and membrane-bound proteins, similar to the role that ClpP plays for cytoplasmic proteins.

PubMed: 18164727
DOI: 10.1016/j.jmb.2007.11.080

Experimental method

X-RAY DIFFRACTION (2.76 Å)