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PDBsum entry 6ix1
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Plant protein
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PDB id
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6ix1
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References listed in PDB file
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Key reference
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Title
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High resolution structural and functional analysis of a hemopexin motif protein from dolichos.
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Authors
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S.C.Sharma,
A.Kumar,
S.Vashisht,
D.M.Salunke.
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Ref.
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Sci Rep, 2019,
9,
19828.
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PubMed id
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Abstract
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It is increasingly evident that seed proteins exhibit specific functions in
plant physiology. However, many proteins remain yet to be functionally
characterized. We have screened the seed proteome of Dolichos which lead to
identification and purification of a protein, DC25. The protein was monomeric
and highly thermostable in extreme conditions of pH and salt. It was
crystallized and structure determined at 1.28 Å resolution using x-ray
crystallography. The high-resolution structure of the protein revealed a
four-bladed β-propeller hemopexin-type fold containing pseudo four-fold
molecular symmetry at the central channel. While the structure exhibited
homology with 2S albumins, variations in the loops connecting the outermost
strands and the differences in surface-charge distribution may be relevant for
distinct functions. Comparative study of the protein with other seed hemopexins
revealed the presence of four conserved water molecules in between the blades
which cross-link them and maintain the tertiary structure. The protein exhibited
intrinsic peroxidase activity, which could be inhibited by binding of a heme
analog. The identification of redox-sensitive cysteine and inhibition of
peroxidase activity by iodoacetamide facilitated characterization of the
possible active site. The determined peroxidase activity of DC25 may be
responsible for rescuing germinating seeds from oxidative stress.
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