The repeat domain of coagulase promotes assembly of a fibrin sheet on the surface of S. aureus. (A) Human plasma (+) or PBS control (–) were subjected to chromatography on Strep-Tactin resin precharged with full-length coagulase (CoaST), coagulase truncated for the R domain (CoaΔR/ST), the R domain (RST) alone, or without affinity bait. Proteins retained on the affinity column were analyzed by Coomassie-stained PAGE or immunoblotting with antibodies against prothrombin. (B) Human plasma or PBS was added to cultures of S. aureus wild-type, the coaΔR variant or medium control (–). Plasma proteins in the supernatant and sedimented fibrin clots were separated by centrifugation, analyzed by Coomassie-stained PAGE, or immunoblotting against Coa. Asterisks identifies albumin whose abundance affects the mobility of CoaΔR. α-, β-, and γ-chains of fibrinogen/fibrin are labeled. (C) S. aureus wild-type or coaΔR expressing mCherry were incubated with human citrate plasma and 5% Alexa Fluor 488–conjugated human fibrinogen and imaged by fluorescence microscopy. Bars, 10 µm. Data are representative of two independent analyses.
