Discovery in plants suggests entirely new approach to treating hum...( repeated the x-ray treatment to determi...)

The scientists learned that auxin is a sort of "molecular glue" that improves the ability of TIR1 to bind its peptide target. In the absence of auxin, TIR1 does not bind its target as tightly.

Because the architecture of TIR1 is highly conserved among other ubiquitin ligases, including those in human cells, the scientists expect other ubiquitin ligases may be affected by small molecules like auxin. Organic chemists could, hypothetically, synthesize such molecules as a new type of cancer drug.

"A number of human disorders including Parkinson's disease, and colon and breast cancers, are caused by defective interactions between ubiquitin ligases and their substrate polypeptides. What the plant hormone tells us is that it might be possible to rescue these interactions using small molecules," said Zheng.

Two teams of scientists reported in May 2005 (also in Nature) that TIR1 is, in fact, a receptor for auxin. Estelle led one of the two teams; Ottoline Leyser of the University of York led the other. The discovery put to end conjecture about how auxin initiates growth and light response in plants, but it also caught the attention of those studying the molecular biology and biochemistry of human ubiquitin ligases.

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Contact: David Bricker
brickerd@indiana.edu
812-856-9035
Indiana University
4-Apr-2007