@article {2695,
	title = {Modulating the Mechanical Stability of Extracellular Matrix Protein Tenascin-C in a Controlled and Reversible Fashion},
	journal = {Journal of Molecular Biology},
	volume = {390},
	number = {4},
	year = {2009},
	note = {ISI Document Delivery No.: 477KYTimes Cited: 2Cited Reference Count: 45Zhuang, Shulin Peng, Qing Cao, Yi Li, Hongbin},
	month = {Jul},
	pages = {820-829},
	type = {Article},
	abstract = {Stretching force can induce conformational changes of proteins and is believed to be an important biological signal in the mechanotransduction network. Tenascin-C is a large extracellular matrix protein and is subject to stretching force under its physiological condition. Regulating the mechanical properties of the fibronectin type III domains of tenascin-C will alter its response to mechanical stretching force and thus may provide the possibility of regulating the biological activities of tenascin-C in living cells. However, tuning the mechanical stability of proteins in a rational and systematic fashion remains challenging. Using the third fibronectin type III domain (TNfn3) of tenascin-C as a model system, here we report a successful engineering of a mechanically stronger extracellular matrix protein via engineered metal chelation. Combining steered molecular dynamics simulations, protein engineering and single-molecule atomic force microscopy, we have rationally engineered a bihistidine-based metal chelation site into TNfn3. We used its metal chelation capability to selectively increase the unfolding energy barrier for the rate-limiting step during the mechanical unfolding of TNfn3. The resultant TNfn3 mutant exhibits enhanced mechanical stability. Using a stronger metal chelator, one can convert TNfn3 back to a state of lower mechanical stability. This is the first step toward engineering extracellular matrix proteins with defined mechanical properties, which can be modulated reversibly by external stimuli, and will provide the possibility of using external stimuli to regulate the biological functions of extracellular matrix proteins. (C) 2009 Elsevier Ltd. All rights reserved.},
	keywords = {DYNAMICS, ELASTICITY, ENGINEERING PROTEINS, FNIII DOMAIN, FRAGMENTS, MECHANICAL STABILITY, mechanical unfolding, microscopy, MOLECULE FORCE SPECTROSCOPY, MUSCLE, rational design, recombination, SINGLE PROTEIN, single-molecule force spectroscopy, tenascin},
	isbn = {0022-2836},
	url = {<Go to ISI>://000268519200019},
	author = {Zhuang, S. L. and Peng, Q. and Cao, Y. and Li, H. B.}
}
@article {2034,
	title = {Single molecule force spectroscopy reveals engineered metal chelation is a general approach to enhance mechanical stability of proteins},
	journal = {Proceedings of the National Academy of Sciences of the United States of America},
	volume = {105},
	number = {32},
	year = {2008},
	note = {ISI Document Delivery No.: 339EKTimes Cited: 16Cited Reference Count: 44Cao, Yi Yoo, Teri Li, Hongbin},
	month = {Aug},
	pages = {11152-11157},
	type = {Article},
	abstract = {Significant mechanical stability is an essential feature shared by many elastomeric proteins, which function as molecular springs in a wide variety of biological machinery and biomaterials of superb mechanical properties. Despite the progress in understanding molecular determinants of mechanical stability, it remains challenging to rationally enhance the mechanical stability of proteins. Using single molecule force spectroscopy and protein engineering techniques, we demonstrate that engineered bi-histidine metal chelation can enhance the mechanical stability of proteins significantly and reversibly. Based on simple thermodynamic cycle analysis, we engineered a bi-histidine metal chelation site into various locations of the small protein, GB1, to achieve preferential stabilization of the native state over the mechanical unfolding transition state of GB1 through the binding of metal ions. Our results demonstrate that the metal chelation can enhance the mechanical stability of GB1 by as much as 100 pN. Since bi-histidine metal chelation sites can be easily implemented, engineered metal chelation provides a general methodology to enhance the mechanical stability of a wide variety of proteins. This general approach in protein mechanics will enable the rational tuning of the mechanical stability of proteins. It will not only open new avenues toward engineering proteins of tailored nanomechanical properties, but also provide new approaches to systematically map the mechanical unfolding pathway of proteins.},
	keywords = {BINDING SITES, charge, DESIGN, DOMAINS, ELASTICITY, engineering, EXTRACELLULAR-MATRIX PROTEIN, mechanical unfolding, PROTEIN, protein mechanics, rational design, SIMULATIONS, STABILIZATION, STRENGTH, THERMOSTABILITY, TITIN},
	isbn = {0027-8424},
	url = {<Go to ISI>://000258560700024},
	author = {Cao, Y. and Yoo, T. and Li, H. B.}
}
@article {4617,
	title = {Cavitands are effective templates for inducing stability and nativelike structure in de Novo four-helix bundles},
	journal = {Journal of the American Chemical Society},
	volume = {121},
	number = {39},
	year = {1999},
	note = {ISI Document Delivery No.: 243QXTimes Cited: 40Cited Reference Count: 92},
	month = {Oct},
	pages = {8983-8994},
	type = {Article},
	abstract = {We have designed, synthesized and characterized eight cavitand-based de novo four-helix bundles, where each helix contains the basis sequence EELLKKLEELLKKG. We find that each de novo protein is highly helical and extremely stable to the chemical denaturant guanidine hydrochloride (GuHCl). We studied the effect of the cavitand-peptide linker on the stability of each de novo protein. Flexible linkers render the helical structures more susceptible to denaturation by GuHCl. Linker structure and length also dictate monomer/dimer equilibria of the proteins. Proteins containing 0-3 Cry units possess varying degrees of nativelike structure. In contrast, proteins containing two or four methylene Linkers are more characteristic of molten globules. These differences can be attributed to the additional hydrogen bonding capabilities of the glycine linker variants and to the distance between the cavitand template and the helical bundle. The cavitand pendent group was also changed in one de novo protein from a methyl group to a propyl-phosphate moiety. This alteration does not affect the stability or packing within the helical bundle; however, it does affect the monomer/dimer equilibrium.},
	keywords = {4-HELIX BUNDLE, ASSEMBLED, conformational, DESIGNED PROTEIN, HOST GUEST COMPLEXATION, HYDROGEN-EXCHANGE, MOLTEN GLOBULE, NONPOLAR AMINO-ACIDS, rational design, STABILITY, SYNTHETIC PROTEINS, ULTRAVIOLET CIRCULAR-DICHROISM},
	isbn = {0002-7863},
	url = {<Go to ISI>://000083009700003},
	author = {Mezo, A. R. and Sherman, J. C.}
}
