Regensburg 2013 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 8: Posters: Proteins

BP 8.8: Poster

Montag, 11. März 2013, 17:30–19:30, Poster B2

Demonstration of catch bonds between glycosaminoglycan and positively charged hydrophilic domain from the cell surface sulfatase Sulf1 — •A.-K. Möller, A. Harder, F. Milz, P. Neuhaus, V. Walhorn, Th. Dierks, and D. Anselmetti — Bielefeld University, Germany

The unique hydrophilic domain (HD) found in the human sulfatases Sulf1 and Sulf2 is responsible for targeting Sulf1 to the cell surface by interacting with its substrate. The enzymatic activity of Sulf1 is known to be specifically directed towards the 6-O-sulfation sites of heparan sulfate (HS) within highly sulfated regions of the glycosaminoglycan. Since the function of many growth and differentiation factors is regulated by HS, which acts as an essential cofactor for the interaction with cell surface localized receptors, these molecular and cellular interactions have great influence on embryogenesis and homeostasis. We used single-molecule AFM force spectroscopy (SMFS) to investigate the specificity of the interaction between HD and the glycosaminoglycans dermatan sulfate (DS) as well as heparin (Hep), the latter serving as model for the interacting regions of HS due to its high sulfation. Thereby we found an increased binding probability by increasing pulling velocity which is similar to experiments on P-selectin and its counterligand PSGL-1. We additionally applied AFM force clamp experiments to measure the force-dependent lifetimes of the interaction. We observed prolonged bond lifetimes under higher tensile forces between 10-20 pN, which we will discuss within the framework of molecular catch bonds.