3DRF: Lactococcal Oppa Complexed With An Endogenous Peptide In The Closed Conformation

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: 3DRFDownload
MMDB ID: 70530
PDB Deposition Date: 2008/7/11
Updated in MMDB: 2011/05
Experimental Method:
x-ray diffraction
Resolution: 1.3  Å
Source Organism:
Lactococcus lactis subsp. cremoris MG1363
Similar Structures:
Biological Unit for 3DRF: dimeric; determined by author and by software (PISA)
Molecular Components in 3DRF
Label Count Molecule
Proteins (2 molecules)
Oligopeptide-binding Protein Oppa
Molecule annotation
Endogenous Peptide
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB