Structural Basis for Ligand Recognition and Discrimination of a Quorum-quenching Antibody.Kirchdoerfer, R.N., Garner, A.L., Flack, C.E., Mee, J.M., Horswill, A.R., Janda, K.D., Kaufmann, G.F., Wilson, I.A.
(2011) J.Biol.Chem. 286: 17351-17358
- PubMed: 21454495
- DOI: 10.1074/jbc.M111.231258
- Primary Citation of Related Structures:
- PubMed Abstract:
In the postantibiotic era, available treatment options for severe bacterial infections caused by methicillin-resistant Staphylococcus aureus have become limited. Therefore, new and innovative approaches are needed to combat such life-threatening infe ...
In the postantibiotic era, available treatment options for severe bacterial infections caused by methicillin-resistant Staphylococcus aureus have become limited. Therefore, new and innovative approaches are needed to combat such life-threatening infections. Virulence factor expression in S. aureus is regulated in a cell density-dependent manner using "quorum sensing," which involves generation and secretion of autoinducing peptides (AIPs) into the surrounding environment to activate a bacterial sensor kinase at a particular threshold concentration. Mouse monoclonal antibody AP4-24H11 was shown previously to blunt quorum sensing-mediated changes in gene expression in vitro and protect mice from a lethal dose of S. aureus by sequestering the AIP signal. We have elucidated the crystal structure of the AP4-24H11 Fab in complex with AIP-4 at 2.5 Å resolution to determine its mechanism of ligand recognition. A key Glu(H95) provides much of the binding specificity through formation of hydrogen bonds with each of the four amide nitrogens in the AIP-4 macrocyclic ring. Importantly, these structural data give clues as to the interactions between the cognate staphylococcal AIP receptors AgrC and the AIPs, as AP4-24H11·AIP-4 binding recapitulates features that have been proposed for AgrC-AIP recognition. Additionally, these structural insights may enable the engineering of AIP cross-reactive antibodies or quorum quenching vaccines for use in active or passive immunotherapy for prevention or treatment of S. aureus infections.
Department of Molecular Biology, The Scripps Research Institute, La Jolla, California 92037, USA.