title: The structural basis for peptide selection by the transport receptor OppA.
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.
authors.affiliation: Biochemistry Department, Groningen Biomolecular Sciences and Biotechnology Institute & Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands.
authors.forename: Ronnie P-A
authors.initials: RP
authors.lastname: Berntsson
authors.forename: Mark K
authors.initials: MK
authors.lastname: Doeven
authors.forename: Fabrizia
authors.initials: F
authors.lastname: Fusetti
authors.forename: Ria H
authors.initials: RH
authors.lastname: Duurkens
authors.forename: Durba
authors.initials: D
authors.lastname: Sengupta
authors.forename: Siewert-Jan
authors.initials: SJ
authors.lastname: Marrink
authors.forename: Andy-Mark W H
authors.initials: AM
authors.lastname: Thunnissen
authors.forename: Bert
authors.initials: B
authors.lastname: Poolman
authors.forename: Dirk-Jan
authors.initials: DJ
authors.lastname: Slotboom
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D013294:Lactococcus lactis / Q000737:chemistry* / Q000378:metabolism*; D008074:Lipoproteins / Q000737:chemistry* / Q000378:metabolism*; D013058:Mass Spectrometry; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D008074:Lipoproteins; D010455:Peptides; C046506:oligopeptide-binding protein, bacteria