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CELL BIOLOGY AND SIGNAL TRANSDUCTION

A Role for F-Actin in Hexokinase-Mediated Glucose Signaling^{1,[C],[W],[OA]}

Department of Genetics and Biochemistry, Clemson University, Clemson, South Carolina 29631 (R.B., A.K., B.d.M.); and Genetics Department, University of Georgia, Athens, Georgia 30602 (M.K., R.B.M.)

HEXOKINASE1 (HXK1) from Arabidopsis (Arabidopsis thaliana) has dual roles in glucose (Glc) signaling and in Glc phosphorylation. The cellular context, though, for HXK1 function in either process is not well understood. Here we have shown that within normal experimental detection limits, AtHXK1 is localized continuously to mitochondria. Two mitochondrial porin proteins were identified as capable of binding to overexpressed HXK1 protein, both in vivo and in vitro. We also found that AtHXK1 can be associated with its structural homolog, F-actin, based on their coimmunoprecipitation from transgenic plants that overexpress HXK1-FLAG or from transient expression assays, and based on their localization in leaf cells after cryofixation. This association might be functionally important because Glc signaling in protoplast transient expression assays is compromised by disruption of F-actin. We also demonstrate that Glc treatment of Arabidopsis seedlings rapidly and reversibly disrupts fine mesh actin filaments. The possible roles of actin in HXK-dependent Glc signaling are discussed.

² These authors contributed equally to the article.

The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Brandon d. Moore (moore8{at}clemson.edu).

^[C] Some figures in this article are displayed in color online but in black and white in the print edition.

^[W] The online version of this article contains Web-only data.

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www.plantphysiol.org/cgi/doi/10.1104/pp.107.108704

^* Corresponding author; e-mail moore8{at}clemson.edu.

Received September 6, 2007; accepted October 22, 2007; published October 26, 2007.

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Plant Physiol. 2007 145: 1301-1302. [Full Text]