Biomaterial Database

Fibrinogen binding is affected by amino acid substitutions in C-terminal repeat region of fibronectin binding protein A. 2019

Nadia N Casillas-Ituarte, and Alex C DiBartola, and Megan J Broughton, and Lumarie Pérez-Guzmán, and Robert M Wheeler, and Makoto Ibaraki, and B Alexis Lower, and James A Dunn, and Brian H Lower, and Vance G Fowler, and Magnus Hӧӧk, and Lauren M McIntyre, and Steven K Lower, and Batu K Sharma-Kuinkel

Ohio State University, Columbus, Ohio, 43210, USA.

Fibronectin-binding protein A (FnBPA), a protein displayed on the outer surface of Staphylococcus aureus, has a structured A-domain that binds fibrinogen (Fg) and a disordered repeat-region that binds fibronectin (Fn). Amino acid substitutions in Fn-binding repeats (FnBRs) have previously been linked to cardiovascular infection in humans. Here we used microtiter and atomic force microscopy (AFM) to investigate adhesion by variants of full-length FnBPA covalently anchored in the outer cell wall of Lactococcus lactis, a Gram-positive surrogate that otherwise lacks adhesins to mammalian ligands. Fn adhesion increased in five of seven FnBPA variants under static conditions. The bond targeting Fn increased its strength with load under mechanical dissociation. Substitutions extended bond lifetime (1/koff) up to 2.1 times for FnBPA-Fn. Weaker adhesion was observed for Fg in all FnBPA variants tested with microtiter. However, mechanical dissociation with AFM showed significantly increased tensile strength for Fg interacting with the E652D/H782Q variant. This is consistent with a force-induced mechanism and suggests that the dock, lock, and latch (DLL) mechanism is favored for Fg-binding under mechanical stress. Collectively, these experiments reveal that FnBPA exhibits bimodal, ligand-dependent adhesive behavior. Amino acid substitutions in the repeat-region of FnBPA impact binding to both ligands. This was unexpected for Fg since all variants have the same A-domain sequence, and the Fg-binding site is distant from the repeat region. This indicates that FnBRs may fold back on the A-domain in a way that impacts the DLL binding mechanism for Fg.

UI	MeSH Term	Description	Entries
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D005340	Fibrinogen	Plasma glycoprotein clotted by thrombin, composed of a dimer of three non-identical pairs of polypeptide chains (alpha, beta, gamma) held together by disulfide bonds. Fibrinogen clotting is a sol-gel change involving complex molecular arrangements: whereas fibrinogen is cleaved by thrombin to form polypeptides A and B, the proteolytic action of other enzymes yields different fibrinogen degradation products.	Coagulation Factor I,Factor I,Blood Coagulation Factor I,gamma-Fibrinogen,Factor I, Coagulation,gamma Fibrinogen
D013211	Staphylococcus aureus	Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications.
D013294	Lactococcus lactis	A non-pathogenic species of LACTOCOCCUS found in DAIRY PRODUCTS and responsible for the souring of MILK and the production of LACTIC ACID.	Streptococcus lactis,Lactococcus lactis subsp. lactis
D018829	Adhesins, Bacterial	Cell-surface components or appendages of bacteria that facilitate adhesion (BACTERIAL ADHESION) to other cells or to inanimate surfaces. Most fimbriae (FIMBRIAE, BACTERIAL) of gram-negative bacteria function as adhesins, but in many cases it is a minor subunit protein at the tip of the fimbriae that is the actual adhesin. In gram-positive bacteria, a protein or polysaccharide surface layer serves as the specific adhesin. What is sometimes called polymeric adhesin (BIOFILMS) is distinct from protein adhesin.	Adhesins, Fimbrial,Bacterial Adhesins,Fimbrial Adhesins,Adhesin, Bacterial,Bacterial Adhesin
D019943	Amino Acid Substitution	The naturally occurring or experimentally induced replacement of one or more AMINO ACIDS in a protein with another. If a functionally equivalent amino acid is substituted, the protein may retain wild-type activity. Substitution may also diminish, enhance, or eliminate protein function. Experimentally induced substitution is often used to study enzyme activities and binding site properties.	Amino Acid Substitutions,Substitution, Amino Acid,Substitutions, Amino Acid
D020079	Terminal Repeat Sequences	Nucleotide sequences repeated on both the 5' and 3' ends of a sequence under consideration. For example, the hallmarks of a transposon are that it is flanked by inverted repeats on each end and the inverted repeats are flanked by direct repeats. The Delta element of Ty retrotransposons and LTRs (long terminal repeats) are examples of this concept.	Delta Elements,Flanking Repeat Sequences,Inverted Terminal Repeat,Long Terminal Repeat,R Repetitive Sequence,Terminal Repeat,Delta Element,Element, Delta,Elements, Delta,Flanking Repeat Sequence,Long Terminal Repeats,R Repetitive Sequences,Repeat Sequence, Flanking,Repeat Sequence, Terminal,Repeat Sequences, Flanking,Repeat Sequences, Terminal,Repeat, Long Terminal,Repeat, Terminal,Repeats, Long Terminal,Repeats, Terminal,Repetitive Sequence, R,Repetitive Sequences, R,Sequence, Flanking Repeat,Sequence, R Repetitive,Sequence, Terminal Repeat,Sequences, Flanking Repeat,Sequences, R Repetitive,Sequences, Terminal Repeat,Terminal Repeat Sequence,Terminal Repeat, Long,Terminal Repeats,Terminal Repeats, Long