4HXE: Pyrococcus horikoshii acylaminoacyl peptidase (uncomplexed)

Oligopeptidases impose a size limitation on their substrates, the mechanism of which has long been under debate. Here we present the structure of a hexameric serine protease, an oligopeptidase from Pyrococcus horikoshii (PhAAP), revealing a complex, self-compartmentalized inner space, where substrates may access the monomer active sites passing through a double-gated "check-in" system, first passing through a pore on the hexamer surface and then turning to enter through an even smaller opening at the monomers' domain interface. This substrate screening strategy is unique within the family. We found that among oligopeptidases, a residue of the catalytic apparatus is positioned near an amylogenic beta-edge, which needs to be protected to prevent aggregation, and we found that different oligopeptidases use different strategies to achieve such an end. We propose that self-assembly within the family results in characteristically different substrate selection mechanisms coupled to different multimerization states.
PDB ID: 4HXEDownload
MMDB ID: 109886
PDB Deposition Date: 2012/11/9
Updated in MMDB: 2017/11
Experimental Method:
x-ray diffraction
Resolution: 1.91  Å
Source Organism:
Similar Structures:
Biological Unit for 4HXE: hexameric; determined by author and by software (PISA)
Molecular Components in 4HXE
Label Count Molecule
Proteins (6 molecules)
Putative Uncharacterized Protein Ph0594
Molecule annotation
Chemicals (54 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB