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PDBsum entry 4yi9
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Calcium binding protein
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PDB id
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4yi9
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References listed in PDB file
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Key reference
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Title
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Crystal structure of recoverin with calcium ions bound to both functional ef hands.
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Authors
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R.P.Kumar,
M.J.Ranaghan,
A.Y.Ganjei,
D.D.Oprian.
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Ref.
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Biochemistry, 2015,
54,
7222-7228.
[DOI no: ]
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PubMed id
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Abstract
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Recoverin (Rv), a small Ca(2+)-binding protein that inhibits rhodopsin kinase
(RK), has four EF hands, two of which are functional (EF2 and EF3). Activation
requires Ca(2+) in both EF hands, but crystal structures have never been
observed with Ca(2+) ions in both sites; all previous structures have Ca(2+)
bound to only EF3. We suspected that this was due to an intermolecular crystal
contact between T80 and a surface glutamate (E153) that precluded coordination
of a Ca(2+) ion in EF2. We constructed the E153A mutant, determined its X-ray
crystal structure to 1.2 Å resolution, and showed that two Ca(2+) ions are
bound, one in EF3 and one in EF2. Additionally, several other residues are shown
to adopt conformations in the 2Ca(2+) structure not seen previously and not seen
in a second structure of the E153A mutant containing Na(+) instead of Ca(2+) in
the EF2 site. The side-chain rearrangements in these residues form a 28 Å
allosteric cascade along the surface of the protein connecting the
Ca(2+)-binding site of EF2 with the active-site pocket responsible for binding
RK.
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