PMID:18164727
| Citation |
Kim, AC, Oliver, DC and Paetzel, M (2008) Crystal structure of a bacterial signal Peptide peptidase. J. Mol. Biol. 376:352-66 |
|---|---|
| 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. |
| Links |
PubMed Online version:10.1016/j.jmb.2007.11.080 |
| Keywords |
Amino Acid Sequence; Aspartic Acid Endopeptidases/chemistry; Aspartic Acid Endopeptidases/isolation & purification; Aspartic Acid Endopeptidases/metabolism; Bacterial Proteins/chemistry; Bacterial Proteins/isolation & purification; Bacterial Proteins/metabolism; Binding Sites; Catalysis; Crystallography, X-Ray; Escherichia coli/enzymology; Escherichia coli Proteins/chemistry; Hydrogen Bonding; Models, Chemical; Models, Molecular; Molecular Sequence Data; Periplasm/enzymology; Protein Binding; Protein Folding; Protein Structure, Secondary; Protein Structure, Tertiary; Sequence Homology, Amino Acid; Serine Endopeptidases/chemistry; Static Electricity; Substrate Specificity; Surface Properties |
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