Daniel S.-C. Yang

Professor, Department of Biochemistry
B.Sc., M.Sc. (Alberta), Ph.D. (Pittsburgh)

Protein crystallography, protein engineering, structure and function of anti-freeze, ice nucleation and bone proteins

Water is an essential element for all living organisms, yet the ambient temperature on earth encompasses in its range of fluctuation the phase transition temperature of water.  The crystallization of water becomes inevitable and its happening poses a severe threat to all living organisms. In addition to preventing water from serving its regular functions, freezing can cause physical damage to cell structures.  Many organisms survive by shying away from a "freezable" environment.  Others developed novel mechanisms to confront the threat of freezing.  Basically, there are two different mechanisms employed by the organisms to cope with their cold surrounding environment.  Some polar marine fishes and over-wintering terrestrial anthropods survive in an ice-laden environment by synthesizing antifreeze proteins which prevent ice crystals from propagating in their
organismic fluid.  These proteins apparently adsorb onto the surfaces of ice crystals and inhibit the growth of these crystals.  Other insects and plant species, on the other hand, possess ice nucleation proteins to induce ice formation in the extracellular fluid at fairly high temperatures.  The avoidance of extensive supercooling is important because otherwise lethal intracellular ice formation might occur. Some insects and plant species possess both ice nucleation proteins and antifreeze proteins. In these cases, the antifreeze proteins have been implicated in playing important roles in slowing down the recrystallization process during freeze-thaw cycles in early fall and spring. The antifreeze
and ice nucleation proteins thus protect the organism from freeze damage by two rather different mechanisms. The major interest of this laboratory is to uncover the structural principles governing protein-ice interactions. The uniqueness of our system of study is that the substrate that we are studying is not a single molecule but a crystal lattice.  Our current understanding of protein's interaction with crystal lattices is very limited. Since ice crystal can have many different faces, and the expression of the various faces are
influenced by the presence of antifreeze proteins, a comprehensive understanding of protein-ice interaction would require studies of the proteins and of the ice systems and this laboratory is set up to do both.

Selected Publications

Identification of the ice-binding surface on a type III AFP with a "flatness function" algorithm. Yang, D.S.C., Hen, W.-C., Bubanko, S., Xue, Y.Q., Seetharaman, J., Hew, C.L. and Sicheri, F.(1998). Biophysical Journal 74: 2142-2151.

The ice-binding site of Atlantic herring antifreeze protein corresponds to the carbohydrate-binding site ofC-type lectins. Ewart, K.V., Li, Z., Yang, D.S.C., Fletcher, G.L. and Hew, C.L. (1998) Biochemistry 37: 4080-4085.

Skin-type antifreeze protein from the shorthorn sculpin (Myoxocephalus scorpius); expression and characterization of a 9,700 M, recombinant protein. Low, W-K., Miao, M., Ewart, V., Yang, D.S.C., Fletcher, G.L. and Hew, C.L. (1998) Journal of Biological Chemishy 273: 23098-23103.

Antifreeze proteins in winter rye.  Griffith, M., Antikainen, M., Hen, W.C., Pihakaski-Maunsbach, P., Yu, X.M., Chun, J.U. and Yang, D.S.C. (1997) Physiologia Plantarum. 100: 327-332.

Structure of an enzyme required for aminoglycoside antibiotic resistance reveals homology to eukaryotic protein kinases.  Hen, W.C., McKay, G.A., Thompson, P.R., Sweet, R.M., Yang, D.S.C., Wright, G.D. and Berghuis, A.M. (1997) Cell 89: 887-895.

Ice binding structure and mechanism of an antifreeze from winter flounder. Sicheri, F. and Yang, D.S.C. (1995) Nature 375: 427-431.

The mechanism of protein crystal growth from lipid layers. Hemming, S.A., Bochkarev, A., Darst, S.A., Kornberg, R.D., Ala, P., Yang, D.S.C. and Edwards, A.M. (1995) J. Mel. Biol. 246: 308-316.

Protein interaction with ice. Hew, C.L. and Yang, D.S.C. (1992) fur. J. Biochem.203:33-42.

Crystal structure of a bovine neurophysin II dipeptide complex at 2.8A determined from the single-wavelength anomalous scattering signal of an incorporated iodine atom. Chen, L., Rose, J.P., Breslow, E., Yang, D., Chang, W.-R., Yoo, C.S., Furey, W.F Jr., Sax, M. and Wang, B.-C.(1991) Proc. Natl. Acad. Sci. USA 88: 4240-4244.