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Title
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Cytokinin-induced structural adaptability of a Lupinus luteus PR-10 protein.
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Authors
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H.Fernandes,
A.Bujacz,
G.Bujacz,
F.Jelen,
M.Jasinski,
P.Kachlicki,
J.Otlewski,
M.M.Sikorski,
M.Jaskolski.
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Ref.
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Febs J, 2009,
276,
1596-1609.
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PubMed id
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Abstract
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Plant pathogenesis-related (PR) proteins of class 10 are the only group among
the 17 PR protein families that are intracellular and cytosolic. Sequence
conservation and the wide distribution of PR-10 proteins throughout the plant
kingdom are an indication of an indispensable function in plants, but their true
biological role remains obscure. Crystal and solution structures for several
homologues have shown a similar overall fold with a vast internal cavity which,
together with structural similarities to the steroidogenic acute regulatory
protein-related lipid transfer domain and cytokinin-specific binding proteins,
strongly indicate a ligand-binding role for the PR-10 proteins. This article
describes the structure of a complex between a classic PR-10 protein [Lupinus
luteus (yellow lupine) PR-10 protein of subclass 2, LlPR-10.2B] and
N,N'-diphenylurea, a synthetic cytokinin. Synthetic cytokinins have been shown
in various bioassays to exhibit activity similar to that of natural cytokinins.
The present 1.95 A resolution crystallographic model reveals four
N,N'-diphenylurea molecules in the hydrophobic cavity of the protein and a
degree of conformational changes accompanying ligand binding. The structural
adaptability of LlPR-10.2B and its ability to bind different cytokinins suggest
that this protein, and perhaps other PR-10 proteins as well, can act as a
reservoir of cytokinin molecules in the aqueous environment of a plant cell.
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