1yhu
From Proteopedia
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'''Crystal structure of Riftia pachyptila C1 hemoglobin reveals novel assembly of 24 subunits.''' | '''Crystal structure of Riftia pachyptila C1 hemoglobin reveals novel assembly of 24 subunits.''' | ||
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[[Category: Royer, W E.]] | [[Category: Royer, W E.]] | ||
[[Category: Schaeffer, S W.]] | [[Category: Schaeffer, S W.]] | ||
| - | [[Category: | + | [[Category: Globin fold]] |
| - | [[Category: | + | [[Category: Hemoglobin]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 16:20:08 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 13:20, 3 May 2008
Crystal structure of Riftia pachyptila C1 hemoglobin reveals novel assembly of 24 subunits.
Overview
Key to the remarkable ability of vestimentiferan tubeworms to thrive in the harsh conditions of hydrothermal vents are hemoglobins that permit the sequestration and delivery of hydrogen sulfide and oxygen to chemoautotrophic bacteria. Here, we demonstrate that zinc ions, not free cysteine residues, bind sulfide in vestimentiferan hemoglobins. The crystal structure of the C1 hemoglobin from the hydrothermal vent tubeworm Riftia pachyptila has been determined to 3.15 A and revealed the unexpected presence of 12 tightly bound Zn(2+) ions near the threefold axes of this D(3) symmetric hollow sphere. Chelation experiments on R. pachyptila whole-coelomic fluid and purified hemoglobins reveal a role for Zn(2+) ions in sulfide binding. Free cysteine residues, previously proposed as sulfide-binding sites in vestimentiferan hemoglobins, are found buried in surprisingly hydrophobic pockets below the surface of the R. pachyptila C1 molecule, suggesting that access of these residues to environmental sulfide is restricted. Attempts to reduce the sulfide-binding capacities of R. pachyptila hemoglobins by addition of a thiol inhibitor were also unsuccessful. These findings challenge the currently accepted paradigm of annelid hemoglobin evolution and adaptation to reducing environments.
About this Structure
1YHU is a Protein complex structure of sequences from Riftia pachyptila. Full crystallographic information is available from OCA.
Reference
Sulfide binding is mediated by zinc ions discovered in the crystal structure of a hydrothermal vent tubeworm hemoglobin., Flores JF, Fisher CR, Carney SL, Green BN, Freytag JK, Schaeffer SW, Royer WE Jr, Proc Natl Acad Sci U S A. 2005 Feb 22;102(8):2713-8. Epub 2005 Feb 14. PMID:15710902 Page seeded by OCA on Sat May 3 16:20:08 2008
