Fig.1 X-ray diffraction pattern of a protein crystal.

M. truncatula functional structural genomics
Xiaoqiang Wang, Ph.D.
Assistant Professor
email: xwang@noble.org

The functions of macromolecules such as proteins are determined by their three dimensional structures. To obtain structural data is very important for us to understand the structure and function relationship. For M. truncatula functional structural genomics, we are working together with the plant biologists, biochemists and genetists here to study the biological important plant proteins involved in natural product biosynthesis, nutrient uptake, DNA repair and other biological processes, using crystallography as the main experimental technique.

We select the functional important target proteins, clone their genes, and express them in E. coli or other expression systems. A small-scale expression screen will be performed to identify conditions that produce the high level expression. Then the large scale productions of proteins will be carried out. After produced proteins on a 10-100mg scale with 99% purity, we will screen about 1,000 crystallization conditions for each target protein and grow the suitable crystals for diffraction experiment. The X-ray analysis will be carried out by the state-of-the-art synchrotron facilities and home source.

Fig. 2. Ribbon diagram of structure of a complex of protein and RNA.

By determining the three dimensional structures of proteins and protein-ligand complexes, we are able to reveal the structural basis of protein functions, the detail interactions between proteins and their binding partners, and the mechanisms of their actions. One of the targets from M. truncatula is isoflavone synthase. Isoflavones, better known as phytoestrogens, are special plant natural products found in legumes and have significant benefits for our health. It's believed that isoflavones may reduce menopausal symptoms, reduce risk of osteoporosis and cancer, and lower cholesteral levels. The key enzyme involved in the production of isoflavones is isoflavone synthase, which is also a member of cytochrome p450 superfamily. There are more than two hundreds of p450 proteins in M. truncatula. The structural study of this important enzyme and/or other p450s will provide us a basis for understanding of the structure-function relationship and the enzymatic mechanism. It will improve our understanding of this biosynthesis process and help us to manipulate the levels of isoflavone in legumes.

See Also:
2001-2002 Scientific Report: Xiaoqiang Wang (pdf)

Research Video: Molecular Biology of Plant Natural Products Flash Player is required

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