Pollen tube guidance towards the ovule is an important step for fertilization in flowering plants. In order for this to happen, a pollen tube attractant peptide LURE guides the pollen tube precisely to the ovule. An international team of plant biologists at Nagoya University and Tsinghua University has succeeded in analyzing for the first time, the crystal structure of LURE bound to its receptor protein PRK6. Further elucidation of this key and lock mechanism may lead to applications in generating useful hybrid plant species.
press released on December 29, 2017
Fig.1: Pollen tube guidance by LURE within the pistil.
The LURE peptide, which is secreted by the synergid cells within the ovule acts as a key to bind to the lock, which is the PRK6 receptor found on the tip of the pollen tube. Figure taken and adapted from the webpage of "The birth of new plant species", a project supported by the Grant-in-Aid for Scientific Research on Innovative Areas (http://www.ige.tohoku.ac.jp/prg/plant/).
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Nagoya, Japan - Fertilization in flowering plants occurs by the delivery of sperm cells to the ovule by the precise growth of pollen tubes from pollen. Pollen tube guidance plays a crucial role in controlling the growth of pollen tubes and a pollen tube attractant peptide LURE is secreted from the synergid cells next to the egg cell within the ovule to lead to successful fertilization. LURE is specific to each plant species and is therefore responsible for the fertilization between the same species.
LURE1 has already been identified in a model plant Arabidopsis thaliana, and there have been reports on the presence of receptors on the pollen tube responsible for detecting LURE1. The key and lock model illustrates the relationship between the LURE peptide (ligand) and its receptor. To which lock (receptor) the key (LURE) binds to and how it does so has been a mystery up to now.
In order to identify the exact receptor on the pollen tube for LURE, Tetsuya Higashiyama, a professor at Nagoya University and his collaborators at Tsinghua University who have expertise in structural biology of plant ligands and receptors, performed analyses of the complexes by X-ray crystallography. The team examined the protein that binds to LURE by making LURE of Arabidopsis thaliana and its protein receptor by cultures of insect cells. As a result, they were able to determine that LURE specifically binds to a protein receptor called PRK6 (pollen receptor-like kinase 6) on the pollen tube. The results of this study are reported in Nature Communications......>>read more on the ITbM website
