PIN Structures Shed Light on Their Mechanism of Auxin Efflux

Original video: https://youtu.be/7r6N6KeGOrk

Polar auxin transport is a quintessential feature of higher plant physiology and it has been known for many years that some of the primary drivers of polar auxin transport are the PIN-formed (PIN) auxin efflux proteins. Formative research established many key biochemical features of the transport system and discovered inhibitors such as 1-naphthylphthalamic acid (NPA), but the mechanism of action of PINs has remained elusive. This changed in 2022 with the publication of high-resolution structures of the membrane-spanning domains of three PIN proteins. The atomic structures and associated activity assays reveal that PINs use an elevator mechanism to transport auxin anions out of the cell. NPA was shown to be a competitive inhibitor that traps PINs in their inward-open conformation. The secrets of the hydrophilic cytoplasmic loop of PIN proteins remain to be discovered. This video series provides an in-depth exploration of the structure and function of three key members of the PIN protein family: PIN8, PIN3, and PIN1. These proteins play critical roles in plant development by facilitating the directional transport of the plant hormone auxin.

Keywords: Auxin, efflux, hormone transport, molecular mechanism, polar, protein structure

Citation: Chitra Joshi, Richard Napier, PIN structures shed light on their mechanism of auxin efflux, Journal of Experimental Botany, Volume 74, Issue 15, 17 August 2023, Pages 4377–4383, https://doi.org/10.1093/jxb/erad185

Published on: 17 May 2023

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