Three-dimensional reconstruction of Macrobdella decora (leech) hemoglobin by cryoelectron microscopy.

AUTOR(ES)

de Haas, F

RESUMO

Macrobdella decora hemoglobin was observed in vitreous ice by cryoelectron microscopy and subjected to three-dimensional reconstruction by the method of random conical tilt series. The refined volume has a resolution of 40 A and a D6 point-group symmetry. Its architecture, with its hexagonal bilayer appearance, resembles those of Lumbricus terrestris (oligochaete) and Eudistylia vancouverii (polychaete). When the reconstruction volume is viewed along its sixfold axis, the vertices of the upper hexagonal layer are rotated 16 degrees clockwise compared to those of the lower layer. In agreement with the "bracelet" model of Vinogradov et al., a central linker complex is decorated by 12 hollow globular substructures. The linker complex is made up of a central hexagonal toroid linked by 12 c5 connections to two bracelets of c3 connections, which are themselves linked via six c4 connections. The portion of the hollow globular substructure corresponding to the dodecamer of globin chains has a local pseudo threefold symmetry and is composed of three elongated structures visible when the volume is displayed at high threshold. The main difference between Macrobdella, Lumbricus, and Eudistylia hemoglobins is the presence in Macrobdella of a central hexagonal toroid instead of a compact flat hexagonal structure.

Documentos Relacionados

• The three-dimensional structure of reovirus obtained by cryo-electron microscopy.
• Three-dimensional structures of maturable and abortive capsids of equine herpesvirus 1 from cryoelectron microscopy.
• Three-dimensional reconstruction of Coxiella burnetii-infected L929 cells by high-voltage electron microscopy.
• The S-layer of Caulobacter crescentus: three-dimensional image reconstruction and structure analysis by electron microscopy.
• Three-dimensional cryoelectron microscopy of dimeric kinesin and ncd motor domains on microtubules.