- Structure and function of selected membrane proteins
- Mechanisms of secretory vesicle fusion with membranes
4152 Molecular Biology Building
Dept. of Biochemistry, Biophysics & Molecular Biology
Iowa State University
Ames, IA 50011
Phone: (515) 294-2530
B.S., Seoul National University,1982
Ph.D., Cornell University, 1990
Postdoctoral Fellow, UCLA, 1990-1993
In Professor Shin’s laboratory a new spin labeling EPR approach is used to study the structure and function of biologically important membrane proteins. The strategy is to site-specifically place a nitroxide spin label in the protein by replacing a native residue with cysteine, which provides a unique labeling sites. Current developments of EPR technology make it possible to obtain information on secondary and tertiary structures as well as membrane topology using spin labeled mutants. Unlike crystallographic methods, the EPR approach does not require crystallization of proteins. Thus, the EPR methods are widely applicable to studies of many important membrane proteins. Furthermore, the mechanistic aspects of the function of the membrane proteins are studied using the time-resolved EPR techniques. Specific areas of current interest include:
The viral envelope proteins: influenza HA and HIV gp160
The influenza virus surface is coated with the HA protein which play a major role in the infection of host cells. The primary function of HA is to bring the viral and cellular membranes close together so that they can fuse. Fusion allows the virus genome into the host cell where it replicates. The protein conformational change and its interaction with the cellular membranes are, however, largely unknown. In our laboratory we express the membrane interacting domain of HA in E. coli. Spin labeling EPR and the crystallographic studies are pursued in parallel to elucidate the mechanism of HA-mediated membrane fusion. Furthermore, the structural organization of HIV gp160, which is directly responsible for cell entry, is similar to HA. Thus, the effort also involves the understanding of the function of HIV gp160.
Transmembrane signal transduction
Every living cell possesses the ability to respond to external signals. Specific receptor proteins in cell membranes recognize light, nutrients, odorants, hormones, and neurotransmitters in order to initiate specific physiological responses in cells. It is remarkable that many functionalre ceptors share the basic structural organization. Thus, each class of receptors might as well have a common signalling mechanism. The primary step in signal transduction is the dynamic response of the receptor which converts a chemical stimulus to a structural message and then transduce it across the membrane through a proper conformational change. Our objective is to define and characterize motion of structural units in the receptor that constitutes transmembrane signal transmission. In our laboratory, the signaling of the bacterial aspartate chemotaxis receptor is studied using spin labeling EPR techniques.
1: Bae W, Choi MG, Hyeon C, Shin YK, Yoon TY. Real-Time Observation of Multiple-Protein Complex Formation with Single-Molecule FRET. J Am Chem Soc. 2013 Jul 17;135(28):10254-7. doi: 10.1021/ja404276g. Epub 2013 Jul 9. PubMed PMID: 23808880.
2: Min D, Kim K, Hyeon C, Cho YH, Shin YK, Yoon TY. Mechanical unzipping and rezipping of a single SNARE complex reveals hysteresis as a force-generating mechanism. Nat Commun. 2013;4:1705. doi: 10.1038/ncomms2692. PubMed PMID: 23591872; PubMed Central PMCID: PMC3644077.
3: Choi BK, Choi MG, Kim JY, Yang Y, Lai Y, Kweon DH, Lee NK, Shin YK. Large α-synuclein oligomers inhibit neuronal SNARE-mediated vesicle docking. Proc Natl Acad Sci U S A. 2013 Mar 5;110(10):4087-92. doi: 10.1073/pnas.1218424110. Epub 2013 Feb 19. PubMed PMID: 23431141; PubMed Central PMCID: PMC3593925.
4: Lai Y, Diao J, Liu Y, Ishitsuka Y, Su Z, Schulten K, Ha T, Shin YK. Fusion pore formation and expansion induced by Ca2+ and synaptotagmin 1. Proc Natl Acad Sci U S A. 2013 Jan 22;110(4):1333-8. doi: 10.1073/pnas.1218818110. Epub 2013 Jan 8. PubMed PMID: 23300284; PubMed Central PMCID: PMC3557091.
5: Yang Y, Oh JM, Heo P, Shin JY, Kong B, Shin J, Lee JC, Oh JS, Park KW, Lee CH, Shin YK, Kweon DH. Polyphenols differentially inhibit degranulation of distinct subsets of vesicles in mast cells by specific interaction with granule-type-dependent SNARE complexes. Biochem J. 2013 Mar 15;450(3):537-46. doi: 10.1042/BJ20121256. PubMed PMID: 23252429.
6: Diao J, Ishitsuka Y, Lee H, Joo C, Su Z, Syed S, Shin YK, Yoon TY, Ha T. A single vesicle-vesicle fusion assay for in vitro studies of SNAREs and accessory proteins. Nat Protoc. 2012 May;7(5):921-34. PubMed PMID: 22582418.
7: Kim JY, Choi BK, Choi MG, Kim SA, Lai Y, Shin YK, Lee NK. Solution single-vesicle assay reveals PIP2-mediated sequential actions of synaptotagmin-1 on SNAREs. EMBO J. 2012 May 2;31(9):2144-55. doi: 10.1038/emboj.2012.57. Epub 2012 Mar 9. PubMed PMID: 22407297; PubMed Central PMCID: PMC3343461.
8: Lai Y, Shin YK. The importance of an asymmetric distribution of acidic lipids for synaptotagmin 1 function as a Ca2+ sensor. Biochem J. 2012 Apr 1;443(1):223-9. doi: 10.1042/BJ20112044. PubMed PMID: 22229667.
9: Yoon TY, Kweon DH, Shin YK. Chasing the trails of SNAREs and lipids along the membrane fusion pathway. Curr Top Membr. 2011;68:161-84. doi: 10.1016/B978-0-12-385891-7.00007-6. Review. PubMed PMID: 21771499.
10: Yang Y, Shin JY, Oh JM, Jung CH, Hwang Y, Kim S, Kim JS, Yoon KJ, Ryu JY, Shin J, Hwang JS, Yoon TY, Shin YK, Kweon DH. Dissection of SNARE-driven membrane fusion and neuroexocytosis by wedging small hydrophobic molecules into the SNARE zipper. Proc Natl Acad Sci U S A. 2010 Dec 21;107(51):22145-50. doi: 10.1073/pnas.1006899108. Epub 2010 Dec 6. PubMed PMID: 21135223; PubMed Central PMCID: PMC3009788.
11: Diao J, Su Z, Ishitsuka Y, Lu B, Lee KS, Lai Y, Shin YK, Ha T. A single-vesicle content mixing assay for SNARE-mediated membrane fusion. Nat Commun. 2010 Aug 10;1:54. doi: 10.1038/ncomms1054. PubMed PMID: 20975723; PubMed Central PMCID: PMC3518844.
12: Shin YK. Mg2+ channel selectivity probed by EPR. Structure. 2010 Jul 14;18(7):759-60. doi: 10.1016/j.str.2010.06.002. PubMed PMID: 20637411; PubMed Central PMCID: PMC2910259.
13: Lee HK, Yang Y, Su Z, Hyeon C, Lee TS, Lee HW, Kweon DH, Shin YK, Yoon TY. Dynamic Ca2+-dependent stimulation of vesicle fusion by membrane-anchored synaptotagmin 1. Science. 2010 May 7;328(5979):760-3. doi: 10.1126/science.1187722. PubMed PMID: 20448186; PubMed Central PMCID: PMC2994549.
14: Diao J, Su Z, Lu X, Yoon TY, Shin YK, Ha T. Single-Vesicle Fusion Assay Reveals Munc18-1 Binding to the SNARE Core Is Sufficient for Stimulating Membrane Fusion. ACS Chem Neurosci. 2010 Mar 17;1(3):168-174. Epub 2010 Jan 14. PubMed PMID: 20300453; PubMed Central PMCID: PMC2841011.
15: Lu B, Song S, Shin YK. Accessory alpha-helix of complexin I can displace VAMP2 locally in the complexin-SNARE quaternary complex. J Mol Biol. 2010 Feb 26;396(3):602-9. doi: 10.1016/j.jmb.2009.12.020. Epub 2009 Dec 21. Erratum in: J Mol Biol. 2010 Apr 23;398(1):174-5. PubMed PMID: 20026076; PubMed Central PMCID: PMC2822017.
16: Chang J, Kim SA, Lu X, Su Z, Kim SK, Shin YK. Fusion step-specific influence of cholesterol on SNARE-mediated membrane fusion. Biophys J. 2009 Mar 4;96(5):1839-46. doi: 10.1016/j.bpj.2008.11.033. PubMed PMID: 19254542; PubMed Central PMCID: PMC2717287.
17: Tong J, Borbat PP, Freed JH, Shin YK. A scissors mechanism for stimulation of SNARE-mediated lipid mixing by cholesterol. Proc Natl Acad Sci U S A. 2009 Mar 31;106(13):5141-6. doi: 10.1073/pnas.0813138106. Epub 2009 Feb 27. PubMed PMID: 19251653; PubMed Central PMCID: PMC2663986.
18: Jung CH, Yang YS, Kim JS, Shin YK, Hwang JS, Son ED, Lee HH, Chung KM, Oh JM, Lee JH, Kweon DH. Inhibition of SNARE-driven neuroexocytosis by plant extracts. Biotechnol Lett. 2009 Mar;31(3):361-9. doi: 10.1007/s10529-008-9878-z. Epub 2008 Nov 20. PubMed PMID: 19023663.
19: Yoon TY, Shin YK. Progress in understanding the neuronal SNARE function and its regulation. Cell Mol Life Sci. 2009 Feb;66(3):460-9. doi: 10.1007/s00018-008-8372-z. Review. PubMed PMID: 18953690.
20: Su Z, Ishitsuka Y, Ha T, Shin YK. The SNARE complex from yeast is partially unstructured on the membrane. Structure. 2008 Jul;16(7):1138-46. doi: 10.1016/j.str.2008.03.018. PubMed PMID: 18611386; PubMed Central PMCID: