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Crystallization and preliminary analysis of crystals of the 24-meric hemocyanin of the emperor scorpion (Pandinus imperator).

Jaenicke E, Pairet B, Hartmann H, Decker H - PLoS ONE (2012)

Bottom Line: Hemocyanins are giant oxygen transport proteins found in the hemolymph of several invertebrate phyla.Subunit interactions within the multisubunit hemocyanin complex lead to diverse allosteric effects such as the highest cooperativity for oxygen binding found in nature.A preliminary analysis of the hemocyanin structure reveals that emperor scorpion hemocyanin crystallizes in the same oxygenated conformation, which is also present in solution as previously shown by cryo-EM reconstruction and small angle x-ray scattering experiments.

View Article: PubMed Central - PubMed

Affiliation: Institut für Molekulare Biophysik, Johannes Gutenberg-Universität, Mainz, Germany. elmar.jaenicke@uni-mainz.de

ABSTRACT
Hemocyanins are giant oxygen transport proteins found in the hemolymph of several invertebrate phyla. They constitute giant multimeric molecules whose size range up to that of cell organelles such as ribosomes or even small viruses. Oxygen is reversibly bound by hemocyanins at binuclear copper centers. Subunit interactions within the multisubunit hemocyanin complex lead to diverse allosteric effects such as the highest cooperativity for oxygen binding found in nature. Crystal structures of a native hemocyanin oligomer larger than a hexameric substructure have not been published until now. We report for the first time growth and preliminary analysis of crystals of the 24-meric hemocyanin (M(W) = 1.8 MDa) of emperor scorpion (Pandinus imperator), which diffract to a resolution of 6.5 Å. The crystals are monoclinc with space group C 1 2 1 and cell dimensions a = 311.61 Å, b = 246.58 Å and c = 251.10 Å (α = 90.00°, β = 90.02°, γ = 90.00°). The asymmetric unit contains one molecule of the 24-meric hemocyanin and the solvent content of the crystals is 56%. A preliminary analysis of the hemocyanin structure reveals that emperor scorpion hemocyanin crystallizes in the same oxygenated conformation, which is also present in solution as previously shown by cryo-EM reconstruction and small angle x-ray scattering experiments.

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Related in: MedlinePlus

Electron density at the active site.Calculated electron density (2F0-FC map, 1σ contour level) of SU-5b A) with all copper and dioxygen atoms included in all 24 subunits of the molecular replacement model, B) with all copper and dioxygen atoms omitted in the molecular replacement model. The molecular replacement model included all side chains, but for reason of clarity only the six histidines coordinating the active site are shown. Color coding: backbone atoms = green, carbon = grey, nitrogen = blue, copper = orange, oxygen = red.
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pone-0032548-g003: Electron density at the active site.Calculated electron density (2F0-FC map, 1σ contour level) of SU-5b A) with all copper and dioxygen atoms included in all 24 subunits of the molecular replacement model, B) with all copper and dioxygen atoms omitted in the molecular replacement model. The molecular replacement model included all side chains, but for reason of clarity only the six histidines coordinating the active site are shown. Color coding: backbone atoms = green, carbon = grey, nitrogen = blue, copper = orange, oxygen = red.

Mentions: The R-factor of the model after molecular replacement was 0.43, which is not unreasonably high taking into account the resolution of the dataset and the fact that no further refinement of the model was made. The quality of the electron density obtained as a result of molecular replacement is very good taking into account its resolution of 6.5 Å (Fig. 3). However, the resulting electron density is likely to be biased by the phases of the search model. A detailed evaluation of model bias as well as refinement of the complete structure are difficult given the enormous size of the protein complex and thus are objective of future work.


Crystallization and preliminary analysis of crystals of the 24-meric hemocyanin of the emperor scorpion (Pandinus imperator).

Jaenicke E, Pairet B, Hartmann H, Decker H - PLoS ONE (2012)

Electron density at the active site.Calculated electron density (2F0-FC map, 1σ contour level) of SU-5b A) with all copper and dioxygen atoms included in all 24 subunits of the molecular replacement model, B) with all copper and dioxygen atoms omitted in the molecular replacement model. The molecular replacement model included all side chains, but for reason of clarity only the six histidines coordinating the active site are shown. Color coding: backbone atoms = green, carbon = grey, nitrogen = blue, copper = orange, oxygen = red.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3293826&req=5

pone-0032548-g003: Electron density at the active site.Calculated electron density (2F0-FC map, 1σ contour level) of SU-5b A) with all copper and dioxygen atoms included in all 24 subunits of the molecular replacement model, B) with all copper and dioxygen atoms omitted in the molecular replacement model. The molecular replacement model included all side chains, but for reason of clarity only the six histidines coordinating the active site are shown. Color coding: backbone atoms = green, carbon = grey, nitrogen = blue, copper = orange, oxygen = red.
Mentions: The R-factor of the model after molecular replacement was 0.43, which is not unreasonably high taking into account the resolution of the dataset and the fact that no further refinement of the model was made. The quality of the electron density obtained as a result of molecular replacement is very good taking into account its resolution of 6.5 Å (Fig. 3). However, the resulting electron density is likely to be biased by the phases of the search model. A detailed evaluation of model bias as well as refinement of the complete structure are difficult given the enormous size of the protein complex and thus are objective of future work.

Bottom Line: Hemocyanins are giant oxygen transport proteins found in the hemolymph of several invertebrate phyla.Subunit interactions within the multisubunit hemocyanin complex lead to diverse allosteric effects such as the highest cooperativity for oxygen binding found in nature.A preliminary analysis of the hemocyanin structure reveals that emperor scorpion hemocyanin crystallizes in the same oxygenated conformation, which is also present in solution as previously shown by cryo-EM reconstruction and small angle x-ray scattering experiments.

View Article: PubMed Central - PubMed

Affiliation: Institut für Molekulare Biophysik, Johannes Gutenberg-Universität, Mainz, Germany. elmar.jaenicke@uni-mainz.de

ABSTRACT
Hemocyanins are giant oxygen transport proteins found in the hemolymph of several invertebrate phyla. They constitute giant multimeric molecules whose size range up to that of cell organelles such as ribosomes or even small viruses. Oxygen is reversibly bound by hemocyanins at binuclear copper centers. Subunit interactions within the multisubunit hemocyanin complex lead to diverse allosteric effects such as the highest cooperativity for oxygen binding found in nature. Crystal structures of a native hemocyanin oligomer larger than a hexameric substructure have not been published until now. We report for the first time growth and preliminary analysis of crystals of the 24-meric hemocyanin (M(W) = 1.8 MDa) of emperor scorpion (Pandinus imperator), which diffract to a resolution of 6.5 Å. The crystals are monoclinc with space group C 1 2 1 and cell dimensions a = 311.61 Å, b = 246.58 Å and c = 251.10 Å (α = 90.00°, β = 90.02°, γ = 90.00°). The asymmetric unit contains one molecule of the 24-meric hemocyanin and the solvent content of the crystals is 56%. A preliminary analysis of the hemocyanin structure reveals that emperor scorpion hemocyanin crystallizes in the same oxygenated conformation, which is also present in solution as previously shown by cryo-EM reconstruction and small angle x-ray scattering experiments.

Show MeSH
Related in: MedlinePlus