Subjects: Biology >> Biophysics submitted time 2016-05-11
Chen, Yunfeng
Hong, Jinsung
Zhu, Cheng
Liu, Baoyu
Ju, Lining
Ji, Qinghua
Ji, Qinghua
Chen, Wei
Chen, Wei
Abstract： Membrane receptor-ligand interactions mediate many cellular functions. Binding kinetics and downstream signaling triggered by these molecular interactions are likely affected by the mechanical environment in which binding and signaling take place. A recent study demonstrated that mechanical force can regulate antigen recognition by and triggering of the T-cell receptor (TCR). This was made possible by a new technology we developed and termed fluorescence biomembrane force probe (fBFP), which combines single-molecule force spectroscopy with fluorescence microscopy. Using an ultra-soft human red blood cell as the sensitive force sensor, a high-speed camera and real-time imaging tracking techniques, the fBFP is of similar to 1 pN (10(-12) N), similar to 3 nm and similar to 0.5 msec in force, spatial and temporal resolution. With the fBFP, one can precisely measure single receptor-ligand binding kinetics under force regulation and simultaneously image binding-triggered intracellular calcium signaling on a single live cell. This new technology can be used to study other membrane receptor-ligand interaction and signaling in other cells under mechanical regulation.
Peer Review Status:
Awaiting Review
Subjects: Biology >> Biophysics submitted time 2016-05-11
Ju, Lining
Zhu, Cheng
Chen, Yunfeng
Zhu, Cheng
Ju, Lining
Chen, Yunfeng
Zhu, Cheng
Ju, Lining
Ju, Lining
Lou, Jizhong
Li, Zhenhai
Abstract： Leucine-rich repeat (LRR) is a versatile motif widely present in adhesive proteins and signal-transducing receptors. The concave structure formed by a group of LRRs is thought to facilitate binding to globular protein domains with increased affinities. However, little is known about the conformational dynamics of LRRs in such a structure, e.g., whether and how force induces conformational changes in LRRs to regulate protein binding and signal transduction. Here we investigated the platelet glycoprotein Ib alpha (GPIb alpha), a demonstrated mechanoreceptor with known crystal structures for the N-terminal domain (GPIb alpha N), as a model for LRR-containing proteins using a combined method of steered molecular dynamics simulations and single-molecule force spectroscopy with a biomembrane force probe. We found that force-induced unfolding of GPIb alpha N starts with LRR2-4 and propagates to other LRRs. Importantly, force-dependent lifetimes of individual VWF-A1 bonds with GPIb alpha are prolonged after LRR unfolding. Enhancement of protein-protein interactions by force-induced LRR unfolding may be a phenomenon of interest in biology.
Peer Review Status:Awaiting Review
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