Biophysical Society Thematic Meeting - June 28-July 1, 2015

New Biological Frontiers Illuminated by Molecular Sensors and Actuators

Poster Abstracts

52-POS Board 52 Chemical Biology Sensors for Membrane Curvature and Lipid Composition Hang Yin . University of Colorado Boulder, Boulder, USA.

Elevated microvesicle (MV) shedding is an indication of cancer metastasis. Selectively sensing the highly curved membrane of MVs may provide a novel strategy for their detection, which renders the potential of developing diagnostic, prognostic, and therapeutic agents. We employed a multidisciplinary approach, utilizing our expertise in computational modeling, membrane biophysics, and cellular assay development to rationally design novel tools that sense and regulate membrane curvature and lipid components. Curved membranes are a common and important attribute in exosomes and microvesicles. Our interest focuses on identifying and designing peptides that can sense membrane curvature based on established elements observed in natural curvature-sensing proteins. We have successfully identified a 25-mer peptide, MARCKS- ED, as well as its D-isomer that can both recognize PS with preferences for highly curved vesicles in a specific manner. These rationally designed agents not only help us to understand the critical protein-lipid interactions but also provide prototypes that may eventually lead to novel cancer biomarkers. These studies provide coveted specific probes for exosomes and microvesicles that may be of diagnostic and prognostic potentials.

53-POS Board 53 RFP Tags for Labeling Secretory Pathway Proteins Mingshu Zhang , Pingyong Xu. Institute of Biophysics,Chinese Academy of Sciences, Beijing, China.

Many RFPs are prone to form artificial puncta when labeling proteins in secretory pathway, which may severely impede their further uses in living cell imaging and multi-color imaging. Here we used an environment sensitive membrane protein Orai1 to report the fusion properties of several commonly used RFPs and revealed that intracellular artificial puncta are actually colocalized with lysosome, indicating pKa value of RFPs is also a key factor for artificial puncta appearance besides monomeric properties. In summary, our current study established a fast and easy method to evaluate RFPs fusion properties and provides a useful guide for choosing appropriate RFP for labeling secretory membrane proteins. Among RFPs tested, mOrange2 is highly recommended based on excellent monomeric property, appropriate pKa and high brightness.

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