| AVS 58th Annual International Symposium and Exhibition | |
| Biomaterial Interfaces Division | Thursday Sessions |
| Session BI-ThP |
| Session: | Biomaterial Interfaces Poster Session |
| Presenter: | Siddharth Shenoy, Carnegie Mellon University |
| Authors: | S. Shenoy, Carnegie Mellon University A. Gericke, Kent State University A.H. Ross, University of Massachusetts Medical School M. Lösche, Carnegie Mellon University and National Institute of Standards and Technology |
| Correspondent: | Click to Email |
PTEN is a phosphatidylinositolphosphate (PIP) phosphatase frequently mutated in human cancer [1]. By lowering PI(3,4,5)P3 levels in the plasma membrane, it functions as an antagonist to PI3-kinase in the regulatory circuit that controls cell proliferation and survival. wt PTEN has only weak affinity to zwitterionic phosphatidylcholine (PC) membranes but a strong interaction with anionic lipids. Its C2 domain was shown to bind in a Ca2+ independent manner to phosphatidylserine (PS) and phosphatidylglycerol (PG), whereas a short N-terminal domain binds specifically to PI(4,5)P2 [2,3]. H93R PTEN is an autism related mutant which has decreased phosphatase activity [4].
Using Surface Plasmon Resonance (SPR), we characterized the affinity of wt and H93R PTEN to tethered bilayer lipid membranes (tBLMs) that contain PC and PS, PC and PI(4,5)P2, and PC, PS and PI(4,5)P2. As compared with wt PTEN, we find that the H93R mutation is sufficient to cause significant increases in the protein's association with lipid membranes containing PS. PI(4,5)P2 enhances the apparent binding constant for both proteins and leads to intriguing binding kinetics of the protein to the membrane. The binding of either protein to membranes containing both PS and PI(4,5)P2 shows a biphasic behavior, suggesting two independent binding sites. This supports the hypothesis of non-competitive binding of the protein to PS and PI(4,5)P2 [5]. We also performed neutron reflectivity experiments to determine the structure and orientation of PTEN bound to the membrane.
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4. R. E. Redfern, et al., Protein Sci. 19 (2010), 1948-1956.
5. R. E. Redfern, et al., Biochemistry 47 (2008), 2162-2171.