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BIOCHEMICAL PROCESSES AND MACROMOLECULAR STRUCTURES

The K-Segment of Maize DHN1 Mediates Binding to Anionic Phospholipid Vesicles and Concomitant Structural Changes^1,[W],[OA]

Graduate Program in Biochemistry and Molecular Biology (M.-C.K., S.W., T.J.C.), Department of Botany and Plant Sciences (M.-C.K., R.D.F., J.R., E.V., T.J.C.), and Department of Biochemistry (S.W.), University of California, Riverside, California 92521–0124

Dehydrins (DHNs; late embryogenesis abundant D11 family) are a family of intrinsically unstructured plant proteins that accumulate in the late stages of seed development and in vegetative tissues subjected to water deficit, salinity, low temperature, or abscisic acid treatment. We demonstrated previously that maize (Zea mays) DHNs bind preferentially to anionic phospholipid vesicles; this binding is accompanied by an increase in -helicity of the protein, and adoption of -helicity can be induced by sodium dodecyl sulfate. All DHNs contain at least one "K-segment," a lysine-rich 15-amino acid consensus sequence. The K-segment is predicted to form a class A2 amphipathic -helix, a structural element known to interact with membranes and proteins. Here, three K-segment deletion proteins of maize DHN1 were produced. Lipid vesicle-binding assays revealed that the K-segment is required for binding to anionic phospholipid vesicles, and adoption of -helicity of the K-segment accounts for most of the conformational change of DHNs upon binding to anionic phospholipid vesicles or sodium dodecyl sulfate. The adoption of structure may help stabilize cellular components, including membranes, under stress conditions.

² Present address: Department of Physiology, University of California, Los Angeles, CA 90095.

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: Timothy J. Close (timothy.close{at}ucr.edu).

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

^[OA] Open Access articles can be viewed online without a subscription.

www.plantphysiol.org/cgi/doi/10.1104/pp.109.136697

^* Corresponding author; e-mail timothy.close{at}ucr.edu.

Received February 5, 2009; accepted May 6, 2009; published May 13, 2009.