Structure of an extracellular giant hemoglobin of the gutless beard worm Oligobrachia mashikoi
AUTOR(ES)
Numoto, Nobutaka
FONTE
National Academy of Sciences
RESUMO
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-Å 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.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1253539Documentos Relacionados
- Bracelet protein: a quaternary structure proposed for the giant extracellular hemoglobin of Lumbricus terrestris.
- Carbohydrate gluing, an architectural mechanism in the supramolecular structure of an annelid giant hemoglobin.
- Non-heme protein in the giant extracellular hemoglobin of the earthworm Lumbricus terrestris.
- Characterization of chemoautotrophic bacterial symbionts in a gutless marine worm Oligochaeta, Annelida) by phylogenetic 16S rRNA sequence analysis and in situ hybridization.
- CYTOLOGICAL DEMONSTRATION OF THE HELICAL STRUCTURE OF GIANT CHROMOSOMES