Browsing by Author "Lin, Chien Y."

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Deciphering the Catalysis-Associated Conformational Changes of Human Adenylate Kinase 1 with Single-Molecule Spectroscopy
(2013-11-14)
Lin, Chien Y.
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Huang, Jung Y.
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Lo, Leu-Wei
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光電工程學系
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Department of Photonics
Human adenylate kinase isoenzyme 1 (AK1) is the key enzyme in maintaining the cellular energy homeostasis. The catalysis-associated conformational changes of AK1 involve large-amplitude rearrangements. To decipher the conformational changes of AK1 at the single-molecule level, we tagged AK1 with two identical fluorophores, one near the substrate-binding site and the other at the boundary of the core domain. We found that magnesium ion binding to AK1 increases the structural heterogeneity of AK1, whereas ADP binding reduces the structural heterogeneity. We exploited the hidden Markov model to extract the underlying catalysis-associated conformational dynamics and determined thermodynamic parameters of the multiple catalytic pathways. The third-order correlation difference calculated from photon fluctuation traces reveals the irreversible nature of the conformational motions, suggesting that single-molecule AK1 is in a nonequilibrium steady state. This discovery offers a fresh viewpoint to look into the molecular mechanisms of cellular biochemistry.
Depicting Binding-Mediated Translocation of HIV-1 Tat Peptides in Living Cells with Nanoscale Pens of Tat-Conjugated Quantum Dots
(2017-02-01)
Lin, Chien Y.
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Huang, Jung Y.
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Lo, Leu-Wei
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田家炳光電中心
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Tin Ka Ping Photonics Center
Cell-penetrating peptides (CPPs) can translocate across cell membranes, and thus have great potential for the cellular delivery of macromolecular cargoes. However, the mechanism of this cellular uptake process is not yet fully understood. In this study, a time-lapse single-particle light-sheet microscopy technique was implemented to obtain a parallel visualization of the translocating process of individual human immunodeficiency virus 1 (HIV-1) transactivator of transcription (Tat) peptide conjugated quantum dots (TatP-QDs) in complex cellular terrains. Here, TatP-QDs served as nanoscale dynamic pens, which depict remarkable trajectory aggregates of TatP-QDs on the cell surface. Spectral-embedding analysis of the trajectory aggregates revealed a manifold formed by isotropic diffusion and a fraction of directed movement, possibly caused by interaction between the Tat peptides and heparan sulfate groups on the plasma membrane. Further analysis indicated that the membrane deformation induced by Tat-peptide attachment increased with the disruption of the actin framework in cytochalasin D (cyto D)-treated cells, yielding higher interactions on the TatP-QDs. In native cells, the Tat peptides can remodel the actin framework to reduce their interaction with the local membrane environment. Characteristic hot spots for interaction were detected on the membrane, suggesting that a funnel passage may have formed for the Tat-coated particles. This finding offers valuable insight into the cellular delivery of nanoscale cargo, suggesting an avenue for direct therapeutic delivery.
Dynamic regulation on energy landscape evolution of single-molecule protein by conformational fluctuation
(2012-08-31)
Lin, Chien Y.
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Huang, Jung Y.
;
Lo, Leu-Wei
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光電工程學系
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Department of Photonics
We formalize a theory to help explore the effect of conformational fluctuation on the energy landscape evolution of single-molecule protein. Using this formalization, we investigate the photon emission from single photoactivated fluorescent protein. A bimodal regulation on the energy landscape evolution was discovered, and its origin was attributed to slow conformational fluctuations of the protein matrix.
Energetic modeling and single-molecule verification of dynamic regulation on receptor complexes by actin corrals and lipid raft domains
(2014-12-07)
Lin, Chien Y.
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Huang, Jung Y.
;
Lo, Leu-Wei
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光電工程學系
;
Department of Photonics
We developed an energetic model by integrating the generalized Langevin equation with the Cahn-Hilliard equation to simulate the diffusive behaviors of receptor proteins in the plasma membrane of a living cell. Simulation results are presented to elaborate the confinement effects from actin corrals and protein-induced lipid domains. Single-molecule tracking data of epidermal growth factor receptors (EGFR) acquired on live HeLa cells agree with the simulation results and the mechanism that controls the diffusion of single-molecule receptors is clarified. We discovered that after ligand binding, EGFR molecules move into lipid nanodomains. The transition rates between different diffusion states of liganded EGFR molecules are regulated by the lipid domains. Our method successfully captures dynamic interactions of receptors at the single-molecule level and provides insight into the functional architecture of both the diffusing EGFR molecules and their local cellular environment. (C) 2014 AIP Publishing LLC.
Energy Landscape Evolution of Single-Molecule Protein Guided by Conformational Fluctuation
(2012-01-31)
Lin, Chien Y.
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Huang, June Y.
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Lo, Leu-Wei
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光電工程學系
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Department of Photonics
Exploring in vivo cholesterol-mediated interactions between activated EGF receptors in plasma membrane with single-molecule optical tracking
(2016-06-24)
Lin, Chien Y.
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Huang, Jung Y.
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Lo, Leu-Wei
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光電工程學系
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田家炳光電中心
Background: The first step in many cellular signaling processes occurs at various types of receptors in the plasma membrane. Membrane cholesterol can alter these signaling pathways of living cells. However, the process in which the interaction of activated receptors is modulated by cholesterol remains unclear. Methods: In this study, we measured single-molecule optical trajectories of epidermal growth factor receptors moving in the plasma membranes of two cancerous cell lines and one normal endothelial cell line. A stochastic model was developed and applied to identify critical information from single-molecule trajectories. Results: We discovered that unliganded epidermal growth factor receptors may reside nearby cholesterol-riched regions of the plasma membrane and can move into these lipid domains when subjected to ligand binding. The amount of membrane cholesterol considerably affects the stability of correlated motion of activated epidermal growth factor receptors. Conclusions: Our results provide single-molecule evidence of membrane cholesterol in regulating signaling receptors. Because the three cell lines used for this study are quite diverse, our results may be useful to shed light on the mechanism of cholesterol-mediated interaction between activated receptors in live cells.
Exploring the stochastic dynamics of correlated movement of receptor proteins in plasma membranes in vivo
(2015-12-14)
Huang, Jung Y.
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Lin, Chien Y.
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交大名義發表
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光電工程學系
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National Chiao Tung University
Ligand-induced receptor dimerization plays a crucial role in the signaling process of living cells. In this study, we developed a theoretical model and performed single-molecule tracking to explore the correlated diffusion processes of liganded epidermal growth factor receptors prior to dimer formation. We disclosed that both an attractive potential between liganded receptor proteins in proximity and correlated fluctuations in the local environments of the proteins play an important role to produce the observed correlated movement of the receptors. This result can serve as the foundation to shed light on the way in which receptor functions are regulated in plasma membranes in vivo. (C) 2015 AIP Publishing LLC.
High-Order Correlated Motion in Single-Molecule Human Adenylate Kinase 1
(2012-01-31)
Lin, Chien Y.
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Huang, Jung Y.
;
Lo, Leu-Wei
;
光電工程學系
;
Department of Photonics
Impact of electric quadrupolar coupling on the optical response of an array of nano-objects
(2010-06-09)
Lin, Chien Y.
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Wang, Yun H.
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Huang, Jung Y.
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Liu, Yongjun
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Zhao, Yiping
Intra- and inter-particle coupling effects are important but have not been properly taken into account in modeling the optical response of an array of nano-objects. In this paper, we present a method to analyze the impact of electric quadrupolar coupling on the optical response of a layer of silver nanorods fabricated with oblique-angle deposition (OAD). Our technique can render the non-locally coupled nano-objects into an array of coarse-grained induced charges. The retrieved polarizability tensor of the silver nanorods exhibits non-zero off-diagonal components, revealing information about the array structure and inter-particle quadrupolar couplings. Thus, a more transparent picture of the correlation between the function and structure of an optical metamaterial can be yielded.
Low cost high-efficiency amorphous silicon solar cells with improved light-soaking stability
(2012-03-01)
Huang, Jung Y.
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Lin, Chien Y.
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Shen, Chang-Hong
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Shieh, Jia-Min
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Dai, Bau-Tong
We investigate the performance of amorphous Si (a-Si) solar cells fabricated with Inductively Coupled Plasma (ICP) deposition technique. The ICP system produces a-Si films with low defect density (3 x 10(15) cm(-3)), resulting in a conversion efficiency of 9.6%. Deep level transient spectroscopy (DLTS) reveals that hole carriers trapped at defects near the valence band edge delocalize at 130 K: while trapped electrons can only be emitted into the conduction band near room temperature. Spectrally resolved DLTS study further indicates that light soaking enhances the emission rate of the tapped electrons near the conduction band edge while reduces the transition moments from the hole-trapping defect levels to the conduction band. The combined effects and light soaking-induced defects are responsible for the degradation of a thin film solar cell by light soaking. (C) 2011 Elsevier B.V. All rights reserved.
Quantum control study of ultrafast optical responses in semiconductor quantum dot devices
(2014-12-15)
Huang, Jung Y.
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Lin, Chien Y.
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Liu, Wei-Sheng
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Chyi, Jen-Inn
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光電工程學系
Two quantum control spectroscopic techniques were applied to study InAs quantum dot (QD) devices, which contain different strain-reducing layers. By adaptively control light matter interaction, a delayed resonant response from the InAs QDs was found to be encoded into the optimal phase profile of ultrafast optical pulse used. We verified the delayed resonant response to originate from excitons coupled to acoustic phonons of InAs QDs with two-dimensional coherent spectroscopy. Our study yields valuable dynamical information that can deepen our understanding of the coherent coupling process of exciton in the quantum-confined systems. (C) 2014 Optical Society of America
Unraveling the impact of lipid domains on the dimerization processes of single-molecule EGFRs of live cells
(2015-03-01)
Lin, Chien Y.
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Huang, Jung Y.
;
Lo, Leu-Wei
;
光電工程學系
;
Department of Photonics
Epidermal growth factor receptor (EGFR/ErbB1) is a transmembrane protein that can drive cell growth and survival via the ligand-induced dimerization of receptors. Because dimerization is a common mechanism for signal transduction, it is important to improve our understanding of how the dimerization process and membrane structure regulate signal transduction. In this study, we examined the effect of lipid nanodomains on the dimerization process of EGFR molecules. We discovered that after ligand binding, EGFR molecules may move into lipid nanodomains. The lipid nanodomains surrounding two liganded EGFRs can merge during their correlated motion. The transition rates between different diffusion states of liganded EGFR molecules are regulated by the lipid domains. Our method successfully captures both the sensitivity of single-molecule processes and statistic accuracy of data analysis, providing insight into the connection between the mobile clustering process of receptors and the hierarchical structure of plasma membrane. (C) 2014 Elsevier B.V. All rights reserved.