4q0k

From Proteopedia

(Difference between revisions)
Jump to: navigation, search
Line 10: Line 10:
<div style="background-color:#fffaf0;">
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
== Publication Abstract from PubMed ==
-
Nodulation is an extraordinary symbiotic interaction between leguminous plants and nitrogen-fixing bacteria (rhizobia) that assimilate atmospheric nitrogen (in root nodules) and convert it into compounds suitable for the plant host. A class of plant hormones called cytokinins are involved in the nodulation process. In the model legume Medicago truncatula, nodulin 13 (MtN13), which belongs to the pathogenesis-related proteins of class 10 (PR-10), is expressed in the outer cortex of the nodules. In general, PR-10 proteins are small and monomeric and have a characteristic fold with an internal hydrophobic cavity formed between a seven-stranded antiparallel beta-sheet and a C-terminal alpha-helix. Previously, some PR-10 proteins not related to nodulation were found to bind cytokinins such as trans-zeatin. Here, four crystal structures of the MtN13 protein are reported in complexes with several cytokinins, namely trans-zeatin, N(6)-isopentenyladenine, kinetin and N(6)-benzyladenine. All four phytohormones are bound in the hydrophobic cavity in the same manner and have excellent definition in the electron-density maps. The binding of the cytokinins appears to be strong and specific and is reinforced by several hydrogen bonds. Although the binding stoichiometry is 1:1, the complex is actually dimeric, with a cytokinin molecule bound in each subunit. The ligand-binding site in each cavity is formed with the participation of a loop element from the other subunit, which plugs the only entrance to the cavity. Interestingly, a homodimer of MtN13 is also formed in solution, as confirmed by small-angle X-ray scattering (SAXS).
+
Pathogenesis-related proteins of class 10 (PR-10) are a family of plant proteins with the same fold characterized by a large hydrophobic cavity that allows them to bind various ligands, such as phytohormones. A subfamily with only approximately 20% sequence identity but with a conserved canonical PR-10 fold have previously been recognized as Cytokinin-Specific Binding Proteins (CSBPs), although structurally the binding mode of trans-zeatin (a cytokinin phytohormone) was found to be quite diversified. Here, it is shown that two CSBP orthologues from Medicago truncatula and Vigna radiata bind gibberellic acid (GA3), which is an entirely different phytohormone, in a conserved and highly specific manner. In both cases a single GA3 molecule is found in the internal cavity of the protein. The structural data derived from high-resolution crystal structures are corroborated by isothermal titration calorimetry (ITC), which reveals a much stronger interaction with GA3 than with trans-zeatin and pH dependence of the binding profile. As a conclusion, it is postulated that the CSBP subfamily of plant PR-10 proteins should be more properly linked with general phytohormone-binding properties and termed phytohormone-binding proteins (PhBP).
-
The landscape of cytokinin binding by a plant nodulin.,Ruszkowski M, Szpotkowski K, Sikorski M, Jaskolski M Acta Crystallogr D Biol Crystallogr. 2013 Dec;69(Pt 12):2365-80. doi:, 10.1107/S0907444913021975. Epub 2013 Nov 19. PMID:24311578<ref>PMID:24311578</ref>
+
Specific binding of gibberellic acid by Cytokinin-Specific Binding Proteins: a new aspect of plant hormone-binding proteins with the PR-10 fold.,Ruszkowski M, Sliwiak J, Ciesielska A, Barciszewski J, Sikorski M, Jaskolski M Acta Crystallogr D Biol Crystallogr. 2014 Jul 1;70(Pt 7):2032-41. doi:, 10.1107/S1399004714010578. Epub 2014 Jun 29. PMID:25004979<ref>PMID:25004979</ref>
-
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br>
+
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
</div>
== References ==
== References ==

Revision as of 06:37, 23 July 2014

Crystal Structure of Phytohormone Binding Protein from Medicago truncatula in complex with gibberellic acid (GA3)

4q0k, resolution 1.34Å

Drag the structure with the mouse to rotate

Proteopedia Page Contributors and Editors (what is this?)

OCA

Retrieved from "http://52.214.119.220/wiki/index.php/4q0k"
Views
Personal tools
Navigation
Toolbox