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Professor Marilyn A Anderson
Department of Biochemistry
La Trobe University
Bundoora, Vic 3086
Email: m.anderson@latrobe.edu.au
Tel: +61-3-9479-1255
Fax: +61-3-9479-2467 or 3969
Homepage: http://www.latrobe.edu.au/biochemistry/labs/anderson/research.html

Female reproductive tissues and wounded leaves of the ornamental tobacco, Nicotiana alata amass high levels of serine proteinase inhibitors (NaPIs) for protection against pests and pathogens. These 6kDa inhibitors accumulate in the vacuole and are derived from multidomain precursor proteins with either four or six proteinase inhibitor domains. When incorporated into artificial diets or expressed in transgenic plants, the 6kDa inhibitors have a significant effect on mortality and growth of Helicoverpa armigera and H. punctigera larvae, the major insect pests on cotton in Australia. We are interested in the potential of these multidomain proteinase inhibitors to enhance insect resistance in transgenic cotton, however, we are aware of the experience of others that proteinase inhibitors often fail to provide sustainable insect protection in transgenic crop plants. Consequently, we have characterised the insect proteinases that are the target for this series of trypsin and chymotrypsin inhibitors and have examined the changes in expression and activity of the enzymes after prolonged exposure to NaPIs in the diet. Larvae that survive on diets containing the NaPIs have elevated levels of chymotrypsin that are insensitive to inhibition by the NaPIs. We are characterising the molecular features of the insect enzymes with a focus on understanding why some are strongly inhibited by the NaPIs while closely related enzymes are unaffected.
Atkinson, A.H., Heath, R.L., Simpson, R., Clarke, A.E. & Anderson, M.A.(1993). Proteinase inhibitors in Nicotiana alata stigmas are derived from a precursor protein which is processed into five homologous inhibitors. The Plant Cell 5, 203-213

Scanlon, M.J., Lee, M.C.S., Anderson, M.A. and Craik, D.J. (1999) Structure of a putative ancestral protein encoded by a single sequence repeat from a multidomain proteinase inhibitor gene from Nicotiana alata. Structure. 7: 793-802.

Lee, M.C.S., Scanlon, M.J., Craik, D.J. and Anderson, M.A. (1999) A novel two-chain proteinase inhibitor generated by circularization of a multidomain precursor protein. Nature Structural Biology. 6: 526-530.

Miller, E.A., Lee, M.C.S., Atkinson, A. and Anderson, M.A. (2000) Identification of a novel four-domain member of the proteinase inhibitor II family from the stigmas of Nicotiana alata. Plant Mol Biol 42, 329-333

Shirra, H.J., Scanlon, M.J., Lee, M.C.S., Anderson, M.A. and Craik, D.J. (2001) The solution structure of C1-T1, a two-domain proteinase inhibitor derived from a circular precursor protein from Nicotiana alata. J. Mol. Biol. 306, 69-79

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