@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 {2456,
	title = {Nanomechanical Properties of Tenascin-X Revealed by Single-Molecule Force Spectroscopy},
	journal = {Journal of Molecular Biology},
	volume = {385},
	number = {4},
	year = {2009},
	note = {ISI Document Delivery No.: 403HJTimes Cited: 4Cited Reference Count: 35Jollymore, Ashlee Lethias, Claire Peng, Qing Cao, Yi Li, Hongbin},
	month = {Jan},
	pages = {1277-1286},
	type = {Article},
	abstract = {Tenascin-X is an extracellular matrix protein and binds a variety of molecules in extracellular matrix and on cell membrane. Tenascin-X plays important roles in regulating the structure and mechanical properties of connective tissues. Using single-molecule atomic force microscopy, we have investigated the mechanical properties of bovine tenascin-X in detail. Our results indicated that tenascin-X is an elastic protein and the fibronectin type III (FnIII) domains can unfold under a stretching force and refold to regain their mechanical stability upon the removal of the stretching force. All the 30 FnIII domains of tenascin-X show similar mechanical stability, mechanical unfolding kinetics, and contour length increment upon domain unfolding, despite their large sequence diversity. In contrast to the homogeneity in their mechanical unfolding behaviors, FnIII domains fold at different rates. Using the 10th FnIII domain of tenascin-X (TNXfn10) as a model system, we constructed a polyprotein chimera composed of alternating TNXfn10 and GB1 domains and used. atomic force microscopy to confirm that the mechanical properties of TNXfn10 are consistent with those of the FnIII domains of tenascin-X These results lay the foundation to further study the mechanical properties of individual FnIII domains and establish the relationship between point mutations and mechanical phenotypic effect on tenascin-X Moreover, our results provided the opportunity to compare the mechanical properties and design of different forms of tenascins. The comparison between tenascin-X and tenascin-C revealed interesting common as well as distinguishing features for mechanical unfolding and folding of tenascin-C and tenascin-X and will open up new avenues to investigate the mechanical. functions and architectural design of different forms of tenascins. (C) 2008 Elsevier Ltd. All rights reserved.},
	keywords = {AFM, BINDING, DEFICIENCY, DOMAINS, FAMILY, FnIII domains, IDENTIFICATION, III MODULES, MECHANICAL STABILITY, mechanical unfolding, microscopy, PROTEIN, single molecule force spectroscopy, tenascin},
	isbn = {0022-2836},
	url = {<Go to ISI>://000263073400022},
	author = {Jollymore, A. and Lethias, C. and Peng, Q. and Cao, Y. and Li, H. B.}
}
@article {1350,
	title = {Single molecule force spectroscopy reveals a weakly populated microstate of the FnIII domains of tenascin},
	journal = {Journal of Molecular Biology},
	volume = {361},
	number = {2},
	year = {2006},
	note = {ISI Document Delivery No.: 074WPTimes Cited: 8Cited Reference Count: 48Cao, Y. Li, Hongbin},
	month = {Aug},
	pages = {372-381},
	type = {Article},
	abstract = {The native states of proteins exist as an ensemble of conformationally similar microstates. The fluctuations among different microstates are of great importance for the functions and structural stability of proteins. Here, we demonstrate that single molecule atomic force microscopy (AFM) can be used to directly probe the existence of multiple folded microstates. We used the AFM to repeatedly stretch and relax a recombinant tenascin fragment TNfnALL to allow the fibronectin type III (FnIII) domains to undergo repeated unfolding/refolding cycles. In addition to the native state, we discovered that some FnIII domains can refold from the unfolded state into a previously unrecognized microstate, N* state. This novel state is conformationally similar to the native state, but mechanically less stable. The native state unfolds at similar to 120 pN, while the N* state unfolds at similar to 50 pN. These two distinct populations of microstates constitute the ensemble of the folded states for some FnIII domains. An unfolded FnIII domain can fold into either one of the two microstates via two distinct folding routes. These results reveal the dynamic and heterogeneous picture of the folded ensemble for some FnIII domains of tenascin, which may carry important implications for the mechanical functions of tenascins in vivo. (c) 2006 Elsevier Ltd. All rights reserved.},
	keywords = {DYNAMICS, fluctuations, FnIII domains, HYDROGEN-EXCHANGE, IMMUNOGLOBULIN, MECHANICAL STABILITY, mechanical unfolding, microscopy, MODULES, PROTEIN-STRUCTURE, scanning probe, single-molecule force spectroscopy, tenascin, TITIN, UNFOLDING PATHWAYS},
	isbn = {0022-2836},
	url = {<Go to ISI>://000239842800014},
	author = {Cao, Y. and Li, H. B.}
}
@article {1621,
	title = {The unfolding and folding dynamics of TNfnALL probed by single molecule force-ramp spectroscopy},
	journal = {Polymer},
	volume = {47},
	number = {7},
	year = {2006},
	note = {ISI Document Delivery No.: 030JETimes Cited: 10Cited Reference Count: 53},
	month = {Mar},
	pages = {2548-2554},
	type = {Article},
	abstract = {Tenascin, an important extracellular matrix protein, is subject to stretching force under physiological conditions and plays important roles in regulating the cell-matrix interactions. Using the recently developed single molecule force-ramp spectroscopy, we investigated the unfolding-folding kinetics of a recombinant tenascin fragment TNfnALL. Our results showed that all the 15 FnIII domains in TNfnALL have similar spontaneous unfolding rate constant at zero force, but show great difference in their folding rate constants. Our results demonstrated that single molecule force-ramp spectroscopy is a powerful tool for accurate determination of the kinetic parameters that characterize the unfolding and folding reactions. We anticipate that single molecule force-ramp spectroscopy will become a versatile addition to the single molecule manipulation tool box and greatly expand the scope of single molecule force spectroscopy. (c) 2006 Elsevier Ltd. All rights reserved.},
	keywords = {ADHESION, DOMAIN, EXPRESSION, III, IMMUNOGLOBULIN, MATRIX PROTEINS, MECHANICAL STABILITY, microscopy, MUSCLE PROTEIN TITIN, tenascin, UBIQUITIN},
	isbn = {0032-3861},
	url = {<Go to ISI>://000236629900037},
	author = {Wang, M. J. and Cao, Y. and Li, H. B.}
}
