2d2n
From Proteopedia
Structure of an extracellular giant hemoglobin of the gutless beard worm Oligobrachia mashikoi
Structural highlights
Function[GLBB1_OLIMA] The extracellular giant hemoglobin is able to bind and transport oxygen and sulfide simultaneously and reversibly at two different sites. [GLBA1_OLIMA] The extracellular giant hemoglobin is able to bind and transport oxygen and hydrosulfide simultaneously and reversibly at two different sites. [GLBB2_OLIMA] The extracellular giant hemoglobin is able to bind and transport oxygen and hydrosulfide simultaneously and reversibly at two different sites. [GLBA2_OLIMA] The extracellular giant hemoglobin is able to bind and transport oxygen and hydrosulfide simultaneously and reversibly at two different sites. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedMouthless 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. 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[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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