AVS 53rd International Symposium
    Biomaterial Interfaces Tuesday Sessions
       Session BI1-TuM

Paper BI1-TuM13
Dynamic Interactions of the Streptococcal C5a Peptidase with Fibronectin

Tuesday, November 14, 2006, 12:00 pm, Room 2001

Session: Microbe-Surface Interactions
Presenter: J.R. Hull, University of Washington
Authors: J.R. Hull, University of Washington
G. Tamura, University of Washington
D.G. Castner, University of Washington
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Group B Streptococci (GBS) are a leading cause of sepsis and meningitis in newborns, and an emerging cause of serious bacterial infections in immunocompromised adults and the elderly. The streptococcal C5a peptidase (ScpB) of GBS is found in virtually all clinical isolates of GBS. ScpB inhibits neutrophil chemotaxis by enzymatically cleaving the complement component C5a. ScpB is a known Fibronectin (Fn) adhesin; however, it only binds to immobilized Fn and not soluble Fn. Therefore, it is unknown whether or not ScpB binds to a conformational determinate of Fn or multiple adjacent Fn molecules. For this study, Surface Plasmon Resonance (SPR) was used to investigate the interactions of soluble Fn with Scp bound the sensor surface. Scp was made as a GST fusion and bound to the sensor surface through a self-assembled monolayer of glutathione. It was found that binding of soluble Fn with Scp is significantly lower than the binding of Scp to immobilized Fn (KD ~4.0 nM). Next, immobilized Fn was probed with Scp attached to an AFM tip via the bifunctional crosslinker pyridyldithio poly(ethylene glycol) succinimidylpropionate. Each step of the tip functionalization was verified by X-ray photoelectron spectroscopy, and static secondary ion mass spectrometry. It was found that the interaction force between immobilized Fn and Scp is roughly 100 pN. With this force value, a force map was made showing where the Fn/ScpB interactions occurred.