3DRJ: Crystal Structure Of Lactococcal Oppa Co-crystallized With Pth-related Peptide In An Open Conformation

Citation:
Abstract
Oligopeptide-binding protein A (OppA) from Lactococcus lactis binds peptides of an exceptionally wide range of lengths (4-35 residues), with no apparent sequence preference. Here, we present the crystal structures of OppA in the open- and closed-liganded conformations. The structures directly explain the protein's phenomenal promiscuity. A huge cavity allows binding of very long peptides, and a lack of constraints for the position of the N and C termini of the ligand is compatible with binding of peptides with varying lengths. Unexpectedly, the peptide's amino-acid composition (but not the exact sequence) appears to have a function in selection, with a preference for proline-rich peptides containing at least one isoleucine. These properties can be related to the physiology of the organism: L. lactis is auxotrophic for branched chain amino acids and favours proline-rich caseins as a source of amino acids. We propose a new mechanism for peptide selection based on amino-acid composition rather than sequence.
PDB ID: 3DRJDownload
MMDB ID: 70534
PDB Deposition Date: 2008/7/11
Updated in MMDB: 2012/09
Experimental Method:
x-ray diffraction
Resolution: 1.5  Å
Source Organism:
Lactococcus lactis subsp. cremoris MG1363
Similar Structures:
Biological Unit for 3DRJ: dimeric; determined by author and by software (PISA)
Molecular Components in 3DRJ
Label Count Molecule
Proteins (2 molecules)
1
Oligopeptide-binding Protein Oppa
Molecule annotation
1
Pth-related Peptide
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB
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