Cytokinin-induced structural adaptability of a Lupinus luteus PR-10 protein.
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.
Fernandes
Humberto
H
Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland.
Bujacz
Anna
A
Bujacz
Grzegorz
G
Jelen
Filip
F
Jasinski
Michal
M
Kachlicki
Piotr
P
Otlewski
Jacek
J
Sikorski
Michal M
MM
Jaskolski
Mariusz
M
D000595:Amino Acid Sequence; D003583:Cytokinins / Q000494:pharmacology*; D031297:Lupinus / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry*; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
D003583:Cytokinins; D010940:Plant Proteins