It is known that the transport of polar auxin is a phenomenon that exists exclusively in plants, as it is responsible for coordinating their growth and development. Scientists also know that auxin transporters of PIN-FORMED (PIN) exhibit asymmetric localizations on the plasma membrane and are responsible for stimulating polar auxin transport. However, the nature of these structural localizations, and the mechanisms of this transport, remain a mystery to scientists. quite.
In this published paper, researchers report the presence of three inward facing structures that constitute the PIN1 enzyme in mouse ear cress. Arabidopsis
thaliana: 1) the state in which the AMP is; 2) the binding form of the natural auxin indole-3-acetic acid (IAA); and 3) the complexity with the N-1-Naphthylphthalamic acid (NPA) auxin polar transport inhibitor. The authors note that the membrane domain of PIN1 shares a conserved NhaA fold.
As reported in the published paper, in the substrate-bound structure, indole-3-acetic acid is coordinated by water aggregation by two effects, namely water repulsion and hydrogen bonding. N-1-naphthylphthalamic acid competes with indole-3-acetic acid for the same position in the intracellular lumen, but with much higher affinity.
These results will enrich scientists’ understanding of the substrate identification and transport mechanisms of PIN enzymes, and provide a framework for future research into the directional transport of auxin, particularly as it is one of the most fundamental processes underlying plant evolution.