Lumbricus Erythrocruorin at 3.5 Å Resolution: Architecture of a Megadalton Respiratory Complex

Abstract

Annelid erythrocruorins are highly cooperative extracellular respiratory proteins with molecular masses on the order of 3.6 million Daltons. We report here the 3.5 A crystal structure of erythrocruorin from the earthworm Lumbricus terrestris. This structure reveals details of symmetrical and quasi-symmetrical interactions that dictate the self-limited assembly of 144 hemoglobin and 36 linker subunits. The linker subunits assemble into a core complex with D(6) symmetry onto which 12 hemoglobin dodecamers bind to form the entire complex. Although the three unique linker subunits share structural similarity, their interactions with each other and the hemoglobin subunits display striking diversity. The observed diversity includes design features that have been incorporated into the linker subunits and may be critical for efficient assembly of large quantities of this complex respiratory protein.

Versatility in ligand recognition by LDL receptor family proteins: advances and frontiers

“…These complexes include the long-range intramolecular interface between LA repeats four and five and the YWTD beta-propeller domain [14], and a VLDLR fragment bound to human rhinovirus serotype 2 (HRV2), for which the LDLR and VLDLR serve as the primary receptor for cell entry [15]. In the structure of the giant erythrocruorin respiratory complex from the earthworm Lumbricus terrestris, interactions between the LA repeats of three linker chains with the hemoglobin b subunits of the complex also exhibit this canonical binding mode with a minor variation: the basic side chains projecting into the acidic pocket are from arginine residues, rather than from lysines [16].…”

Ferric species of the giant extracellular hemoglobin of Glossoscolex paulistus as function of pH: An EPR study on the irreversibility of the heme transitions

“…These include the cooper-containing hemocyanins, from arthropods, mollusks, and heme-containing respiratory proteins, such as those found in annelid worms. The most prevalent of these annelid complexes is known as either erythrocruorins or hexagonal bilayer hemoglobins (HBL) (Royer et al, 2006). Indeed, among the four types of existing respiratory proteins (hemocyanins, hemerytrins, chlorocruorins and hemoglobins) hemoglobins are the more widely distributed in vertebrate and invertebrate animals (Arndt and Santoro, 1998).…”

“…Indeed, HbLt was the first protein reported to be crystallized, in 1840 by Hünefeld, one of the first proteins investigated in Svedberg's initial ultracentrifugation experiments and an early molecular subject of electron microscopy (Royer et al, 2006). Quaternary structure of this protein presents approximately 180 polypeptide chains, involving 144 globin subunits and 36 nonglobin chains.…”

Estudo da estabilidade térmica da hemoglobina extracelular gigante de Glossoscolex paulistus (HbGp): efeitos do estado de oxidação do ferro do grupo heme, pH e presença de surfactante

“…2B e 2C, [3,6] 2B). O papel das subunidades linkers está provavelmente relacionado com a manutenção da estrutura íntegra na forma de bicamada hexagonal [7][8][9].…”

“…Keywords: Extracellular hemoglobin, HbGp, optical absorption, CD, DLS, SAXS, temperature, pH Figura 17: Curvas teóricas de SAXS, obtidas usando o programa CRYSOL [32], e baseados na estrutura cristalográfica da HbLt, depositada no PDB código 2GTL [8]. (A) Curvas de SAXS para a proteína íntegra e fragmentos com maior peso molecular e (B) para os fragmentos com menor peso molecular.…”