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PDBsum entry 5yjs
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Plant protein
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PDB id
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5yjs
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References listed in PDB file
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Key reference
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Title
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Structure-Guided identification of function: role of capsicum annuum vicilin during oxidative stress.
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Authors
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M.Shikhi,
D.T.Nair,
D.M.Salunke.
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Ref.
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Biochem J, 2018,
475,
3057-3071.
[DOI no: ]
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PubMed id
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Abstract
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Proteins belonging to cupin superfamily are known to have critical and diverse
physiological functions. However, 7S globulins family, which is also a part of
cupin superfamily, were undermined as only seed storage proteins. Structure
determination of native protein - Vic_CAPAN from Capsicum annuum - was
carried out, and its physiological functions were explored after purifying the
protein by ammonium sulfate precipitation followed by size exclusion
chromatography. The crystal structure of vicilin determined at 2.16 Å
resolution revealed two monomers per asymmetric unit which are juxtaposed
orthogonal with each other. Vic_CAPAN consists predominately of β-sheets that
folds to form a β-barrel structure commonly called cupin fold. Each monomer of
Vic_CAPAN consists of two cupin fold domains, N-terminal and C-terminal, which
accommodate two different ligands. A bound ligand was identified at the
C-terminal cupin fold in the site presumably conserved for metabolites in the
crystal structure. The ligand was confirmed to be salicylic acid through mass
spectrometric analysis. A copper-binding site was further observed near the
conserved ligand-binding pocket, suggesting possible superoxide dismutase
activity of Vic_CAPAN which was subsequently confirmed biochemically. Vicilins
from other sources did not exhibit this activity indicating functional
specificity of Vic_CAPAN. Discovery of bound salicylic acid, which is a known
regulator of antioxidant pathway, and revelation of superoxide dismutase
activity suggest that Vic_CAPAN has an important role during oxidative stress.
As salicylic acid changes the redox state of cell, it may act as a downstream
signal for various pathways involved in plant biotic and abiotic stress rescue.
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