Protein ice nucleators

A new approach to study root exudation of distinct compounds in soil-grown plants uses inoculation of roots with genetically engineered reporter bacteria, which are able to indicate the presence of particular compounds by indicator reactions, such as production of ice-nucleation proteins. This technique has been employed to detect the release of amino acids from roots of soil-grown A vena harbata (56). 

A technique utilizing genetically modified bacteria to report the presence of particular compounds in soil has also been developed (37). These bacteria respond to the presence of specific compounds in their environment by producing ice-nucleation proteins that enter into cell membranes, enabling cells to be detected by means of a droplet freezing assay. The presence of trytophan in 1-10 i molar concentrations has been detected using reporter bacteria in a study examining loss of amino acids from roots of Avena barbata into soil (38). 

How does the presence of ice-nucleating protein affect the freezing point of water ... 

Form a hypothesis about the effect an ice-nucleating protein will have on the freezing temperature of water. Record your hypothesis on page 98. 

Pour 10 mL of distilled water into the test tube and then use a spatula to add 4 or 5 granules of ice-nucleating protein to the water. 

Jung, H.C., Lebeault, J.M. and Pan, J.G. (1998) Surface display of Zymomonas mobilis levansucrase by using the ice-nucleation protein of Pseudomonas syringae. Nature Biotechnology, 16, 576-580. 

Jung, H.C., Park, J.H., Park, S.H. et al. (1998) Expression of carboxymethylcellulaseonthe surface of Escherichia coli using Pseudomonas syringae ice nucleation protein. Enzyme and Microbial Technology, 22, 348-354. 

Shimazu, M., Mulchandani, A. and Chen, W. (2001) Cell surface display of organophosphorus hydrolase using ice nucleation protein. Biotechnology Progress, 17, 76-80. 

Conformations of Five- and Six-Membered Ring Forms 191 Box4-D Antifreeze and Ice-Nucleation Proteins... 

Duman, 2001 Duman et al., 1993 Wu and Duman, 1991). When its ice-nucleating activity is inhibited, the THP-activator protein does not jeopardize the deep supercooling that may be critical for survival of D. canadensis during periods of extreme cold. 

Duman, J.G. (2001). Antifreeze and ice nucleator proteins in terrestrial arthropods. Annu. Rev. Physiol. 63 327-357. 

Proteins from certain bacteria are ice nucleators (Wolber et ai, 1986). An AFGP inhibits this nucleation, apparently by binding to the bacterial protein. 

P.K. Wolber and G.J. Warren, Evolutionary perspective on the ice nucleation gene-encoded membrane protein in Microbial Ecology of Leaves, eds., J.H. Andrews and S.S. Hirano, Springer-Verlag, New York, 1991, pp.315-330. 

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