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物理学院“博约学术论坛”系列报告第27期

发布日期:2012年09月10日

题 目: Interpreting ligand-dependent allostery: how does the key open the door?

报告人:Professor Lei Zhou 
Department of Physiology and Biophysics

Virginia Commonwealth University School of Medicine
1101 E Marshall St, Sanger Hall 03-012j

时 间:2012年9月11日(星期二)10:00

地 点:中心教学楼701

Abstract:
Ligand-dependent allostery is a basic mechanism through which protein functions are being regulated. Even though this topic has been intensively investigated, it is still unclear how the ligand binding is remotely coupled to the activation of protein function. Three general models have been proposed for protein allostery: the lock-and-key model, the induced-fit model, and the pre-existing equilibrium or conformation-selective model. The contemporary understanding is that protein molecules in different functional states co-exist; ligand binds to the active form with a higher affinity and thus stabilizes the protein in the active state, which shifts the distribution of the protein state equilibrium from the resting state to the active state. Here we used the Hyperpolarization-activated cAMP-regulated HCN channel as a model system to study the ligand-dependent protein allostery. To specifically measure the binding of cAMP to the full-length channel at different functional states, we employed a house-built patch-clamp fluorometry setup, which enables simultaneous electrical recording of channel activity and optical recording of fluorescent-cAMP binding. Our results showed that the channels in the open state have a higher binding affinity for cAMP than those in the resting state do. Furthermore, we asked at the whole molecule level how discrete domains contribute to the cAMP – whole channel interaction, which is dynamic and state-dependent. Our study provided new insights into the cAMP-dependent regulation of HCN channel as well as the basic understanding of the protein allostery, an important and universally existing mechanism that regulates protein function.
Curriculum Vitae:Education
1992        B.S., Department of Physics, Biophysics Program, Nankai University, China
2000        Ph.D., Department of Physiology, University of Wisconsin-Madison
Adviser:   Prof. Shing-Yan (Bill) Chiu
Dissertation:  Physiological and molecular analysis of potassium channel  functions in mammalian myelinated nerves
Employment
2000-2005 Howard Hughes Medical Institute Postdoctoral Research Fellow
 Laboratory of Prof. Steven A. Siegelbaum, Center for Neurobiology & Behavior
 Columbia University / HHMI, New York
2005-2008 Associate Research Scientist
 Laboratory of Prof. Steven A. Siegelbaum, Center for Neurobiology & Behavior
 Columbia University, New York
2008   Assistant Professor
                        Department of Physiology and Biophysics
                        Virginia Commonwealth University School of Medicine
Honors and Awards
1990 First-class Scholarship, Nankai University, China
1991 Guanghua Scholarship, Nankai University, China
1991 Shen-Shou Chun Experimental Physics Prize, Nankai University, China
2000  18th Jerzy E. Rose Neuroscience Award
 University of Wisconsin-Madison, School of Medicine
Research Experience
1990 – 1992 (undergraduate research)
Biophysics Program, Department of Physics, Nankai University
• Predicting the secondary structure of surface antigen of Hepatitis B
• A portable NMR signal detector used in adjusting the magnetic field of mass spectrometer
1996 – 2000 (graduate research)
Laboratory of Prof. Shing-Yan (Bill) Chiu, University of Wisconsin-Madison
• Characterizing the phenotype of Kv1.1 knockout mice in peripheral nervous system (PNS)
• Characterizing the biogenesis and membrane trafficking of Kv channels in Kv?2-null mice
• Computer modeling of myelinated nerve fiber-presynaptic terminal and branch points
2000 – 2008 (postdoctoral research)
Laboratory of Prof. Steven A. Siegelbaum, Columbia University, New York
• Identification of a gating switch preventing the functional expression of CNG ?-subunit 
• Residue contacts critical for ligand binding, selectivity and gating in HCN channels
• Contribution of surface water to protein dynamics studied by a novel coarse-grained normal mode approach

Publications

1. Marni F, Wu S, Shah GM, Xu XP, Hackett AR, Xie C, Shrestha S, Liu L, Liu Q, Zhou L. Normal-Mode-Analysis-Guided Investigation of Crucial Intersubunit Contacts in the cAMP-Dependent Gating in HCN Channels. Biophys J. 2012 Jul 3;103(1):19-28.

2. Wu S, Gao W, Xie C, Xu X, Vorvis C, Marni F, Hackett AR, Liu Q, Zhou L. Inner activation gate in S6 contributes to the state-dependent binding of cAMP in full-length HCN2 channel. J Gen Physiol. 2012 Jul;140(1):29-39.

3. Zhou L. Ion channels: Cooperativity in twin gatings. Nat Chem Biol. 2012 Jan 18;8(2):136-7. (news and views)

4. Xu X, Sarbeng EB, Vorvis C, Kumar DP, Zhou L, Liu Q. Unique peptide substrate binding properties of 110-kDa heat-shock protein (Hsp110) determine its distinct chaperone activity. J Biol Chem. 2012 Feb 17;287(8):5661-72.

5. Wu S, Vysotskaya ZV, Xu X, Xie C, Liu Q, Zhou L. (2011) State-dependent cAMP Binding to Functioning HCN Channels Studied by Patch-Clamp Fluorometry. Biophysical Journal. 100(5):1226-32. (cover story)

6. Xu X*, Vysotskaya ZV*, Liu Q, Zhou L. (2010) Structural basis for the cAMP-dependent gating in the human HCN4 channel. Journal of Biological Chemistry. 285(47):37082-91. PMID: 20829353

7. Bell DC, Turbendian HK, Valley MT, Zhou L, Riley JH, Siegelbaum SA, Tibbs GR (2009) Probing S4 and S5 segment proximity in mammalian hyperpolarization-activated HCN channels by disulfide bridging and Cd2+ coordination. Pflugers Arch. 458(2):259-72. PMID: 19034494

8. Zhou L, Siegelbaum SA. (2008) Pathway and endpoint free energy calculations for cyclic nucleotide binding in HCN channel. Biophysical Journal 94 (12) pp. L90 - L92

9. Zhou L*, Siegelbaum SA. (2008) Effects of surface water on protein dynamics studied by a novel coarse-grained normal mode approach. Biophysical Journal, 94(9):3461-74. (*corresponding author)

10. Zhou L, Siegelbaum SA. (2007) Gating of HCN channels by cyclic-nucleotides: residue contacts that underlie ligand binding, selectivity and efficacy. Structure (Cell Press), 15(6):655-70.

11. Chen S, Wang J, Zhou L, George MS, Siegelbaum SA. (2007) Dual allosteric regulation of voltage-independent opening of HCN channels by voltage-sensor movement and cAMP binding. Journal of General Physiology, 129(2):175-88. 

12. Zhou L, Olivier NB, Yao H, Young EC, Siegelbaum SA. (2004) A Conserved Tripeptide in CNG and HCN Channels Regulates Ligand Gating by Controlling C-Terminal Oligomerization. Neuron (Cell Press), 44(5):823-34.

13. McCormack K, Connor JX, Zhou L, Ho LL, Ganetzky B, Chiu SY, Messing A. (2002) Genetic Analysis of the Mammalian K+ Channel ?-subunit Kv?2 (KCNAB2) Journal of Biological Chemistry, 277(15):13219-28.

14. Zhou L, Chiu SY. (2001) A computer model for action potential propagation through branch point of myelinated nerve. Journal of Neurophysiology, 85:197-210.

15. Wrabetz L, Feltri ML, Quattrini A, Imperiale D, Previtali S, D'Antonio M, Martini R, Yin        X,  Trapp BD, Zhou L, Chiu SY, and Messing A. (2000) P0 Glycoprotein Overexpression Causes Congenital Hypomyelination of Peripheral Nerves. Journal of Cell Biology, 148:1021-1034.

16. Chiu SY, Zhou L, Zhang CL, Messing (1999) Analysis of Potassium Channel Function in Mammalian Axons by Gene knockouts. Journal of Neurocytology, 28:349-364 (Review).

17. Arroyo E, Xu YT, Zhou L, Messing A, Peles E, Chiu SY, Scherer SS (1999)     Myelinating Schwann Cells determine the internodal localization of Kv1.1, Kv1.2 and Caspr. Journal of Neurocytology, 28:333-347.                  

18. Zhou L, Messing A, Chiu SY (1999) Determinants of excitability at transition zones in Kv1.1-deficient myelinated nerves. Journal of Neuroscience, 19:5768-81.      

19. Zhou L, Zhang CL, Messing A, Chiu SY (1998) Temperature-sensitive neuromuscular transmission in Kv1.1 null mice: role of potassium channels under the myelin sheath in young nerves. Journal of Neuroscience, 18:7200-15.

Presentations
1. Xu X, Vysotskaya ZV, Liu Q, Zhou L. Structural and biochemical study of cAMP-dependent regulation of human HCN4 channel. Annual Meeting of Biophysical Society, 2011. (poster 566)
2. Zhou L, Siegelbaum SA Effects of surface water on protein dynamics studied by a novel coarse-grained normal mode approach. Annual Meeting of Biophysical Society, 2008. (poster)
3. Zhou L, Zhu J, Honig B, Siegelbaum SA. A combined physiological and computational study on the binding of cyclic nucleotides to HCN channels. Annual Meeting of Biophysical Society, 2006. (platform)
4. Zhou L, Olivier NB, Siegelbaum SA Drive or Reverse? A Tripeptide Transmission Switch for Gating CNG and HCN Channels by Cyclic Nucleotide. Annual Meeting of Biophysical Society, 2004. (platform)
5. Zhou L, Siegelbaum SA Three amino acids critical for gating in the C-linker of CNG channels Annual Meeting of Biophysical Society, 2003. (Poster)
6. Zhou L, Siegelbaum SA Rescue of non-expressing olfactory CNG channel beta-subunit by replacement of its C-linker with alpha-subunit sequence.  Annual Meeting of Biophysical Society, 2002. (platform)  
7. McCormack K, Connor JX, Zhou L, Ho LL, Ganetzky B, Chiu SY, Messing A  Biogenesis and targeting of potassium channel subunits in Kvbeta2-null mice. Annual Meeting of Society for Neuroscience, 2001. (Poster)
8. Scherer SS, Xu YT, Zhou L, and Chiu SY Myelinating Schwann Cells determine the internodal localization of Kv1.1, Kv1.2 and Caspr/paranodin. Annual Meeting of Society for Neuroscience, 1998. (Poster) 
9. Zhou L, Messing A, Chiu SY  Sensitivity of Kv1.1-null mice to TEA. Annual Meeting of Society for Neuroscience, 1997. (Poster)
10. Zhou L, Messing A, Chiu SY Modulation of neuromuscular transmission in Shaker K channel Kv1.1 knockout mice. Annual Meeting of Society for Neuroscience, 1997. (Poster)
 

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