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Light plays an essential role in intracellular distribution of auxin efflux carrier PIN2 in Arabidopsis thaliana

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Title Light plays an essential role in intracellular distribution of auxin efflux carrier PIN2 in Arabidopsis thaliana
 
Creator Laxmi, Ashverya
Pan, Jianwei
Morsy, Mustafa
Chen, Rujin
 
Subject Arabidopsis thaliana
Auxin Efflux Carrier PIN2
Intracellular Distribution
Light
 
Description Light plays a key role in multiple plant developmental processes. It has been shown that root development is
modulated by shoot-localized light signaling and requires shoot-derived transport of the plant hormone, auxin. However, the
mechanism by which light regulates root development is not largely understood. In plants, the endogenous auxin, indole-3-acetic
acid, is directionally transported by plasma-membrane (PM)-localized auxin influx and efflux carriers in transporting cells.
Remarkably, the auxin efflux carrier PIN proteins exhibit asymmetric PM localization, determining the polarity of auxin transport.
Similar to PM-resident receptors and transporters in animal and yeast cells, PIN proteins undergo constitutive cycling between the
PM and endosomal compartments. Auxin plays multiple roles in PIN protein intracellular trafficking, inhibiting PIN2 endocytosis at
some concentrations and promoting PIN2 degradation at others. However, how PIN proteins are turned over in plant cells is yet to
be addressed. Methodology and Principle Findings. Using laser confocal scanning microscopy, and physiological and molecular
genetic approaches, here, we show that in dark-grown seedlings, the PM localization of auxin efflux carrier PIN2 was largely
reduced, and, in addition, PIN2 signal was detected in vacuolar compartments. This is in contrast to light-grown seedlings where
PIN2 was predominantly PM-localized. In light-grown plants after shift to dark or to continuous red or far-red light, PIN2 also
accumulated in vacuolar compartments. We show that PIN2 vacuolar targeting was derived from the PM via endocytic trafficking
and inhibited by HY5-dependent light signaling. In addition, the ubiquitin 26S proteasome is involved in the process, since its
inhibition by mutations in COP9 and a proteasome inhibitor MG132 impaired the process. Conclusions and Significance.
Collectively, our data indicate that light plays an essential role in PIN2 intracellular trafficking, promoting PM-localization in the
presence of light and, on the other hand, vacuolar targeting for protein degradation in the absence of light. Based on these results,
we postulate that light regulation of root development is mediated at least in part by changes in the intracellular distribution of
auxin efflux carriers, PIN proteins, in response to the light environment.
Funds were provided by the National Science Foundation (DBI-00400580) for purchasing the Laser Confocal Scanning Microscope used in this study. Financial support for the work done in the corresponding author’s
laboratory was from the Samuel Roberts Noble Foundation.
 
Date 2013-11-11T04:33:53Z
2013-11-11T04:33:53Z
2008
29 December 2007
 
Type Article
 
Identifier PLoS ONE, 3(1): e1510
http://hdl.handle.net/123456789/93
 
Language en
 
Publisher PLOS