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PDBsum entry 1cpc
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Light harvesting protein
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PDB id
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1cpc
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Isolation, Crystallization, Crystal structure analysis and refinement of constitutive c-Phycocyanin from the chromatically adapting cyanobacterium fremyella diplosiphon at 1.66 a resolution.
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Authors
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M.Duerring,
G.B.Schmidt,
R.Huber.
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Ref.
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J Mol Biol, 1991,
217,
577-592.
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PubMed id
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Abstract
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Constitutive phycocyanin from cyanobacterium Fremyella diplosiphon (Calothrix
sp. PCC 7601) grown in green light, has been isolated and crystallized. The
crystals belong to the space group R3 with cell constants a = b = 180.26 A, c =
61.24 A, alpha = beta = 90 degrees, gamma = 120 degrees. The crystal structure
has been determined by Patterson search techniques using the molecular model of
C-phycocyanin from the cyanobacterium Agmenellum quadruplicatum. The asymmetric
unit of the crystal cell consists of two (alpha beta)-monomers related by a
local dyad. Three asymmetric units are arranged around a crystallographic triad
and form an (alpha beta)6-hexamer, the functional unit in the native antenna
rod. The initial structure has been refined in a cyclic manner by
energy-restrained crystallographic refinement and modelling until the
conventional crystallographic R-factor converged at 18.1% with data to a
resolution of 1.66 A. The molecular structure resembles closely the
C-phycocyanins of Mastigocladus laminosus and A. quadruplicatum. The
conformation and configuration of the alpha-84 and beta-84 chromophores is very
similar to the corresponding chromophores in the trimeric C-phycocyanin of M.
laminosus, whereas the beta-155 chromophore differs in configuration with
C(4)-Z, C(10)-Z and C(15)-Z compared to C(4)-Z, C(10)-Z, C(15)-Z,E. The
stereochemistry of the beta-155 chiral centres is C(2)-RC(3)-R and C(31)-S,
respectively, whereas alpha-84 and beta-84 have C(2)-RC(3)-R and C(31)-R. The
amino acid sequences of constitutive and inducible phycocyanin differ mainly in
residues located on the surface of the beta-subunits that mediate the
inter-hexameric contacts.
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