Scanning probe microscopy methodologies have advanced to the point that in situ measurements of complex biological systems can be routinely measured at the single-molecule level1, providing information on rare states that can be lost in standard ensemble measurements2and allowing highly specific detection of various proteins and polysaccharides3,4. One such system that has attracted considerable attention is that of the cell signaling pathway Slit-Roundabout (Robo), which has been implicated in the development of the nervous and cardiac systems and in tumorigenesis5. The Slit-Robo complex is stabilized and regulated by heparan sulfate, a linear, structurally-heterogeneous polysaccharide expressed widely on mammalian cell membranes6. Thus, better understanding of heparan sulfates regulatory role could allow us to target therapies related to this pathway7. Using dynamic force spectroscopic methods8, this research shows that is possible to create a model system allowing for the measurement of single-molecule interactions between the heparan sulfate variant heparin and the Robo1 protein, elucidating the kinetics of the interaction using the entire polysaccharide and in ambient conditions.
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(2) Norregaard, K.; Metzler, R.; Ritter, C. M.; Berg-Sørensen, K.; Oddershede, L. B. Manipulation and Motion of Organelles and Single Molecules in Living Cells. Chem. Rev.2017, 117(5), 4342–4375.
(3) Reese, R. Alexander; Xu, B. Single-Molecule Detection of Proteins and Toxins in Food Using Atomic Force Microscopy. Trends Food Sci. Technol.2019, 83(September 2017), 277–284.
(4) Zhang, Y.; Zhang, M.; Reese, R. Alexander; Zhang, H.; Xu, B. Real-Time Single Molecular Study of a Pretreated Cellulose Hydrolysis Mode and Individual Enzyme Movement. Biotechnol. Biofuels2016, 9(1), 85.
(5) Zhao, J.; Mommersteeg, M. T. M. Slit-Robo Signalling in Heart Development. Cardiovasc. Res.2018, 114(6), 794–804.
(6) Blockus, H.; Chédotal, A. The Multifaceted Roles of Slits and Robos in Cortical Circuits: From Proliferation to Axon Guidance and Neurological Diseases. Current Opinion in Neurobiology. 2014, pp 82–88.
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(8) Guo, C.; Wang, B.; Wang, L.; Xu, B. Structural Basis of Single Molecular Heparin-FX06 Interaction Revealed by SPM Measurements and Molecular Simulations. Chem. Commun.2012, 3(100), 12222–12224.