5WXU

11S globulin from Wrightia tinctoria reveals auxin binding site

Summary for 5WXU

• Entry DOI: 10.2210/pdb5wxu/pdb
• Descriptor: 11S globulin, PHOSPHATE ION, CITRATE ANION, ... (7 entities in total)
• Functional Keywords: auxin natural source, plant protein
• Biological source: Wrightia tinctoria
• Total number of polymer chains: 6
• Total formula weight: 327614.77

Authors

Kumar, P.,Kesari, P.,Dhindwal, S.,Kumar, P. (deposition date: 2017-01-09, release date: 2018-05-23, Last modification date: 2024-10-16)

Primary citation

Kumar, P.,Kesari, P.,Dhindwal, S.,Choudhary, A.K.,Katiki, M.,Verma, A.,Ambatipudi, K.,Tomar, S.,Sharma, A.K.,Mishra, G.,Kumar, P.
A novel function for globulin in sequestering plant hormone: Crystal structure of Wrightia tinctoria 11S globulin in complex with auxin.
Sci Rep, 7:4705-4705, 2017

PubMed Abstract: Auxin levels are tightly regulated within the plant cell, and its storage in the isolated cavity of proteins is a measure adopted by cells to maintain the availability of auxin. We report the first crystal structure of Wrightia tinctoria 11S globulin (WTG) in complex with Indole-3-acetic acid (IAA), an auxin, at 1.7 Å resolution. WTG hexamers assemble as a result of the stacking interaction between the hydrophobic surfaces of two trimers, leaving space for the binding of charged ligands. The bound auxin is stabilized by non-covalent interactions, contributed by four chains in each cavity. The presence of bound ligand was confirmed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and high-resolution mass spectrometry (HRMS). Here, we hypothesize that the cleavage of globulins by endopeptidases leads to the movement of the hydrophilic loop region from the surface to the periphery, leaving space for the binding of auxin, and promotes hexamer formation. As the process of germination proceeds, there is a change in the pH, which induces the dissociation of the hexamer and the release of auxin. The compact hexameric assembly ensures the long-term, stable storage of the hormone. This suggests a role for globulin as a novel player in auxin homeostasis.

PubMed: 28680092
DOI: 10.1038/s41598-017-04518-7

Experimental method

X-RAY DIFFRACTION (1.7 Å)