Scientists from the University of Washington School of Medicine, Indiana University Bloomington and the University of Cambridge for the first time have determined how a plant hormone -- auxin -- interacts with its hormone receptor called TIR1.
Their report, on the cover of a recent issue of Nature, may go beyond implications for plant life; it also may have important applications for the treatment of human disease.
TIR1, as it turns out, is similar to human enzymes that are known to be involved in cancer.
The scientists extracted and purified TIR1 from the common plant model Arabidopsis. By X-raying crystals of the protein, they determined the enzyme's three-dimensional structure -- a first for plant-hormone receptors.
The scientists then soaked the crystal in a solution containing auxin and repeated the X-ray treatment to determine where the auxin had bound. Lastly, the scientists added a peptide, learning that auxin improves the ability of TIR1 to bind its peptide target.