7ZOS image
Entry Detail
PDB ID:
7ZOS
Keywords:
Title:
Class 1 Phytoglobin from Sugar beet (BvPgb1.2)
Biological Source:
Source Organism:
PDB Version:
Deposition Date:
2022-04-26
Release Date:
2022-09-07
Method Details:
Experimental Method:
Resolution:
1.90 Å
R-Value Free:
0.23
R-Value Work:
0.20
R-Value Observed:
0.20
Space Group:
P 4 21 2
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Non-symbiotic hemoglobin class 1
Chain IDs:A
Chain Length:171
Number of Molecules:1
Biological Source:Beta vulgaris
Primary Citation
Oxidative Implications of Substituting a Conserved Cysteine Residue in Sugar Beet Phytoglobin BvPgb 1.2.
Antioxidants 11 ? ? (2022)
PMID: 36009334 DOI: 10.3390/antiox11081615

Abstact

Phytoglobins (Pgbs) are plant-originating heme proteins of the globin superfamily with varying degrees of hexacoordination. Pgbs have a conserved cysteine residue, the role of which is poorly understood. In this paper, we investigated the functional and structural role of cysteine in BvPgb1.2, a Class 1 Pgb from sugar beet (Beta vulgaris), by constructing an alanine-substituted mutant (Cys86Ala). The substitution had little impact on structure, dimerization, and heme loss as determined by X-ray crystallography, size-exclusion chromatography, and an apomyoglobin-based heme-loss assay, respectively. The substitution significantly affected other important biochemical properties. The autoxidation rate increased 16.7- and 14.4-fold for the mutant versus the native protein at 25 °C and 37 °C, respectively. Thermal stability similarly increased for the mutant by ~2.5 °C as measured by nano-differential scanning fluorimetry. Monitoring peroxidase activity over 7 days showed a 60% activity decrease in the native protein, from 33.7 to 20.2 U/mg protein. When comparing the two proteins, the mutant displayed a remarkable enzymatic stability as activity remained relatively constant throughout, albeit at a lower level, ~12 U/mg protein. This suggests that cysteine plays an important role in BvPgb1.2 function and stability, despite having seemingly little effect on its tertiary and quaternary structure.

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