22JW

Perinereis linea erythrocruorin

Summary for 22JW

• Entry DOI: 10.2210/pdb22jw/pdb
• EMDB information: 68387
• Descriptor: Extracellular globin A, Extracellular globin B, Extracellular globin C, ... (8 entities in total)
• Functional Keywords: invertebrate, annelid, hemoglobin, erythrocruorin, oxygen transport
• Biological source: Perinereis linea; More
• Total number of polymer chains: 15
• Total formula weight: 279372.25

Authors

Deng, J.X.,Jiang, Y.L.,Zhou, C.Z. (deposition date: 2026-01-14, release date: 2026-08-12)

Primary citation

Deng, J.X.,Cheng, W.B.,Xu, K.,Hou, P.,Chen, Y.,Jiang, Y.L.,Zhou, C.Z.
Structure of Perinereis linea erythrocruorin reveals a compact extracellular globin megacomplex.
Structure, 2026

PubMed Abstract: Many invertebrates lack erythrocytes and instead rely on extracellular hemoglobin assemblies, termed erythrocruorins, for oxygen transport. Here we report a 2.84 Å cryo-electron microscopy (cryo-EM) structure of Perinereis linea erythrocruorin (PlEc). PlEc is a ∼3.3 MDa megacomplex composed of 180 polypeptide chains organized into 12 protomers, forming a hexagonal bilayer with D6 symmetry. Each protomer consists of 12 globin subunits and three linker subunits, adopting a mushroom-like architecture. The cap of the mushroom is formed by a globin dodecamer associated with a heterotrimeric linker head, and the stem consists of a triple-stranded coiled coil derived from the N-terminal helices of three linker subunits. Biochemical assays show that PlEc has thermal stability and auto-oxidation rate comparable to those of other erythrocruorins, but displays relatively lower oxygen-binding affinity. These findings provide mechanistic insights into the quaternary assembly of invertebrate erythrocruorins and lay the groundwork for the potential biomedical applications.

PubMed: 42398506
DOI: 10.1016/j.str.2026.06.004

Experimental method

ELECTRON MICROSCOPY (2.84 Å)