title: Amino acid polymorphisms in the fibronectin-binding repeats of fibronectin-binding protein A affect bond strength and fibronectin conformation.
abstract: TheStaphylococcus aureuscell surface contains cell wall-anchored proteins such as fibronectin-binding protein A (FnBPA) that bind to host ligands (e.g.fibronectin; Fn) present in the extracellular matrix of tissue or coatings on cardiac implants. Recent clinical studies have found a correlation between cardiovascular infections caused byS. aureusand nonsynonymous SNPs in FnBPA. Atomic force microscopy (AFM), surface plasmon resonance (SPR), and molecular simulations were used to investigate interactions between Fn and each of eight 20-mer peptide variants containing amino acids Ala, Asn, Gln, His, Ile, and Lys at positions equivalent to 782 and/or 786 in Fn-binding repeat-9 of FnBPA. Experimentally measured bond lifetimes (1/koff) and dissociation constants (Kd=koff/kon), determined by mechanically dissociating the Fn·peptide complex at loading rates relevant to the cardiovascular system, varied from the lowest-affinity H782A/K786A peptide (0.011 s, 747 μm) to the highest-affinity H782Q/K786N peptide (0.192 s, 15.7 μm). These atomic force microscopy results tracked remarkably well to metadynamics simulations in which peptide detachment was defined solely by the free-energy landscape. Simulations and SPR experiments suggested that an Fn conformational change may enhance the stability of the binding complex for peptides with K786I or H782Q/K786I (Kdapp= 0.2-0.5 μm, as determined by SPR) compared with the lowest-affinity double-alanine peptide (Kdapp= 3.8 μm). Together, these findings demonstrate that amino acid substitutions in Fn-binding repeat-9 can significantly affect bond strength and influence the conformation of Fn upon binding. They provide a mechanistic explanation for the observation of nonsynonymous SNPs infnbAamong clinical isolates ofS. aureusthat cause endovascular infections.
authors.affiliation: From Ohio State University, Columbus, Ohio 43210.
authors.forename: Nadia N
authors.initials: NN
authors.lastname: Casillas-Ituarte
authors.affiliation: the Aggeu Magalhães Institute, Oswaldo Cruz Foundation, Recife, PE, 50.740-465, Brazil, and.
authors.forename: Carlos H B
authors.initials: CHB
authors.lastname: Cruz
authors.affiliation: the Aggeu Magalhães Institute, Oswaldo Cruz Foundation, Recife, PE, 50.740-465, Brazil, and roberto.lins@cpqam.fiocruz.br.
authors.forename: Roberto D
authors.initials: RD
authors.lastname: Lins
authors.affiliation: From Ohio State University, Columbus, Ohio 43210.
authors.forename: Alex C
authors.initials: AC
authors.lastname: DiBartola
authors.affiliation: From Ohio State University, Columbus, Ohio 43210.
authors.forename: Jessica
authors.initials: J
authors.lastname: Howard
authors.affiliation: the Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas 77030.
authors.forename: Xiaowen
authors.initials: X
authors.lastname: Liang
authors.affiliation: the Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas 77030.
authors.forename: Magnus
authors.initials: M
authors.lastname: Höök
authors.affiliation: the Aggeu Magalhães Institute, Oswaldo Cruz Foundation, Recife, PE, 50.740-465, Brazil, and.
authors.forename: Isabelle F T
authors.initials: IFT
authors.lastname: Viana
authors.affiliation: From Ohio State University, Columbus, Ohio 43210.
authors.forename: M Roxana
authors.initials: MR
authors.lastname: Sierra-Hernández
authors.affiliation: From Ohio State University, Columbus, Ohio 43210, Lower.9@osu.edu.
authors.forename: Steven K
authors.initials: SK
authors.lastname: Lower
mesh_terms: D018829:Adhesins, Bacterial / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D019943:Amino Acid Substitution; D018625:Microscopy, Atomic Force; D020125:Mutation, Missense; D020641:Polymorphism, Single Nucleotide; D020449:Repetitive Sequences, Amino Acid; D013211:Staphylococcus aureus / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D020349:Surface Plasmon Resonance
chemical_list: D018829:Adhesins, Bacterial; C078635:fibronectin-binding proteins, bacterial
keywords: Staphylococcus aureus (S. aureus); atomic force microscopy (AFM); binding; bond; energy; fibronectin; ligand; molecular dynamics; single-nucleotide polymorphism (SNP); surface plasmon resonance (SPR)