2d2m
From Proteopedia
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Structure of an extracellular giant hemoglobin of the gutless beard worm Oligobrachia mashikoi
Overview
Mouthless and gutless marine animals, pogonophorans and vestimentiferans, obtain their nutrition solely from their symbiotic chemoautotrophic, sulfur-oxidizing bacteria. These animals have sulfide-binding 400-kDa, and/or 3,500-kDa Hb, which transports oxygen and sulfide simultaneously., The symbiotic bacteria are supplied with sulfide by Hb of the host animal, and use it to provide carbon compounds. Here, we report the crystal, structure of a 400-kDa Hb from pogonophoran Oligobrachia mashikoi at, 2.85-A resolution. The structure is hollow-spherical, composed of a total, of 24 globins as a dimer of dodecamer. This dodecameric assemblage would, be a fundamental structural unit of both 400-kDa and 3,500-kDa Hbs. The, structure of the mercury derivative used for phasing provides insights, into the sulfide-binding mechanism. The mercury compounds bound to all, free Cys residues that have been expected as sulfide-binding sites. Some, of the free Cys residues are surrounded by Phe aromatic rings, and mercury, atoms come into contact with these residues in the derivative structure., It is strongly suggested that sulfur atoms bound to these sites could be, stabilized by aromatic-electrostatic interactions by the surrounding Phe, residues.
About this Structure
2D2M is a Protein complex structure of sequences from Oligobrachia mashikoi with HEM and OXY as ligands. Full crystallographic information is available from OCA.
Reference
Structure of an extracellular giant hemoglobin of the gutless beard worm Oligobrachia mashikoi., Numoto N, Nakagawa T, Kita A, Sasayama Y, Fukumori Y, Miki K, Proc Natl Acad Sci U S A. 2005 Oct 11;102(41):14521-6. Epub 2005 Oct 3. PMID:16204001
Page seeded by OCA on Thu Nov 8 13:28:56 2007
