Lupinus luteus Pathogenesis-Related Protein as a Reservoir for Cytokinin

Plant pathogenesis-related (PR) proteins of class 10 (PR-10) are small and cytosolic. The main feature of their three-dimensional structure is a large cavity between a seven-stranded antiparallel β-sheet and a long C-terminal α-helix. Although PR-10 proteins are abundant in plants, their physiologic...

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Bibliographic Details
Published in:Journal of molecular biology 2008-05, Vol.378 (5), p.1040-1051
Main Authors: Fernandes, Humberto, Pasternak, Oliwia, Bujacz, Grzegorz, Bujacz, Anna, Sikorski, Michal M., Jaskolski, Mariusz
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Binding Sites
Crystallography, X-Ray
cytokinin
Cytokinins - chemistry
Cytokinins - metabolism
Lupinus - chemistry
Molecular Sequence Data
Molecular Structure
Plant Growth Regulators - chemistry
Plant Growth Regulators - metabolism
plant hormones
plant PR-10 protein
Plant Proteins - chemistry
Plant Proteins - metabolism
Protein Binding
Protein Folding
Protein Structure, Tertiary
Sequence Alignment
trans-zeatin
yellow lupine
Zeatin - chemistry
Zeatin - metabolism
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Summary:Plant pathogenesis-related (PR) proteins of class 10 (PR-10) are small and cytosolic. The main feature of their three-dimensional structure is a large cavity between a seven-stranded antiparallel β-sheet and a long C-terminal α-helix. Although PR-10 proteins are abundant in plants, their physiological role remains unknown. Recent data have indicated ligand binding as their possible biological function. The article describes the structure of a complex between a classic PR-10 protein (yellow lupine LlPR-10.2B) and the plant hormone, trans-zeatin. Previously, trans-zeatin binding has been reported in a structurally related cytokinin-specific binding protein, which has a distant sequence relation with classic PR-10 proteins. In the present 1.35 Å resolution crystallographic model, three perfectly ordered zeatin molecules are found in the binding cavity of the protein. The fact that three zeatin molecules are bound by the protein when only a fourfold molar excess of the ligand was used indicates an unusual type of affinity for this ligand and suggests that LlPR-10.2B, and perhaps other PR-10 proteins as well, acts as a reservoir of cytokinin molecules in the aqueous environment of the cell.
ISSN:0022-2836
1089-8638
DOI:10.1016/j.jmb.2008.03.027