2V25

Structure of the Campylobacter jejuni antigen Peb1A, an aspartate and glutamate receptor with bound aspartate

Summary for 2V25

• Entry DOI: 10.2210/pdb2v25/pdb
• Descriptor: MAJOR CELL-BINDING FACTOR, ASPARTIC ACID, ZINC ION, ... (4 entities in total)
• Functional Keywords: antigen, adhesin, aspartate, glutamate, transport, abc transport, virulence factor, campylobacter jejuni, receptor
• Biological source: CAMPYLOBACTER JEJUNI
• Cellular location: Cell surface: Q0P9X8
• Total number of polymer chains: 2
• Total formula weight: 56967.19

Authors

Muller, A.,Dodson, E.,del Rocio Leon-Kempis, M.,Kelly, D.J.,Wilkinson, A.J.,Wilson, K.S. (deposition date: 2007-06-01, release date: 2007-06-26, Last modification date: 2023-12-13)

Primary citation

Muller, A.,Del Rocio Leon-Kempis, M.,Dodson, E.,Wilson, K.S.,Wilkinson, A.J.,Kelly, D.J.
A Bacterial Virulence Factor with a Dual Role as an Adhesin and a Solute Binding-Protein: The Crystal Structure at 1.5 A Resolution of the Peb1A Protein from the Food-Borne Human Pathogen Campylobacter Jejuni
J.Mol.Biol., 372:160-, 2007

PubMed Abstract: The PEB1a protein is an antigenic factor exposed on the surface of the food-borne human pathogen Campylobacter jejuni, which has a major role in adherence and host colonisation. PEB1a is also the periplasmic binding protein component of an aspartate/glutamate ABC transporter essential for optimal microaerobic growth on these dicarboxylic amino acids. Here, we report the crystal structure of PEB1a at 1.5 A resolution. The protein has a typical two-domain alpha/beta structure, characteristic of periplasmic extracytoplasmic solute receptors and a chain topology related to the type II subfamily. An aspartate ligand, clearly defined by electron density in the interdomain cleft, forms extensive polar interactions with the protein, the majority of which are made with the larger domain. Arg89 and Asp174 form ion-pairing interactions with the main chain alpha-carboxyl and alpha-amino-groups, respectively, of the ligand, while Arg67, Thr82, Lys19 and Tyr156 co-ordinate the ligand side-chain carboxyl group. Lys19 and Arg67 line a positively charged groove, which favours binding of Asp over the neutral Asn. The ligand-binding cleft is of sufficient depth to accommodate a glutamate. This is the first structure of an ABC-type aspartate-binding protein, and explains the high affinity of the protein for aspartate and glutamate, and its much weaker binding of asparagine and glutamine. Stopped-flow fluorescence spectroscopy indicates a simple bimolecular mechanism of ligand binding, with high association rate constants. Sequence alignments and phylogenetic analyses revealed PEB1a homologues in some Gram-positive bacteria. The alignments suggest a more distant homology with GltI from Escherichia coli, a known glutamate and aspartate-binding protein, but Lys19 and Tyr156 are not conserved in GltI. Our results provide a structural basis for understanding both the solute transport and adhesin/virulence functions of PEB1a.

PubMed: 17631313
DOI: 10.1016/J.JMB.2007.06.041

Experimental method

X-RAY DIFFRACTION (1.49 Å)