As you read this article, your body is being regulated by various hormones to maintain your health. Just like humans, plants also rely on phytohormones for growth and reproduction. One such phytohormone is the brassinosteroid (BR) hormone, known as the sixth phytohormone.
Brassinosteroid (BR) hormones are crucial for plant development, physiology, and adaptation to environmental stresses. They have significant economic benefits and are widely used in agriculture. While previous studies have shed light on their synthesis and signaling processes, the mechanism of how synthesized BR is exported to carry out its function has remained a mystery. However, a recent discovery of the first BR exporter, ABCB19, marks a major breakthrough in this area.
ABCB19, previously known as a transporter protein for another phytohormone, auxin, has been found to have a mutant phenotype that does not entirely match typical auxin transporter proteins. This led the researchers to question whether ABCB19 has substrates other than auxin.
The researchers conducted various tests to support their hypothesis. They found that the ATPase activity of ABCB19 can be stimulated by bioactive brassinosteroids, but not by auxins or brassinosteroid-biosynthesis precursors. Additionally, they used in vitro and in vivo assays to evaluate the transport of brassinosteroids by ABCB19.
Using cryo-electron microscopy, the researchers observed the process of ABC19 exporting brassinosteroids and identified the unique architecture of ABC19 that allows it to bind with brassinosteroids.
2024-03-21 16:00:04
Original from phys.org
