Unlocking the mystery of pollen tube guidance

ScienceDaily | 12/29/2017 | Staff
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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.

Order - Receptor - Pollen - Tube - LURE

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.

The research team succeeded in obtaining and analyzing the crystal structure of LURE bound to the PRK6 receptor. As a result of their analyses, they found that LURE is bound by being inserted between the leucine-rich repeat region and the transmembrane region of the PRK6 receptor.

LURE - Region

LURE is bound to a region...
(Excerpt) Read more at: ScienceDaily
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