3QJO

Refined Structure of the functional unit (KLH1-H) of keyhole limpet hemocyanin

Summary for 3QJO

• Entry DOI: 10.2210/pdb3qjo/pdb
• Descriptor: Hemocyanin 1, COPPER (II) ION (2 entities in total)
• Functional Keywords: pf00264, oxygen binding, hemolymph
• Biological source: Megathura crenulata (Giant keyhole limpet)
• Total number of polymer chains: 2
• Total formula weight: 113501.78

Authors

Jaenicke, E.,Buchler, K.,Decker, H.,Markl, J.,Schroder, G.F. (deposition date: 2011-01-30, release date: 2011-05-25, Last modification date: 2023-11-01)

Primary citation

Jaenicke, E.,Buchler, K.,Decker, H.,Markl, J.,Schroder, G.F.
The refined structure of functional unit h of keyhole limpet hemocyanin (KLH1-h) reveals disulfide bridges.
Iubmb Life, 63:183-187, 2011

PubMed Abstract: Hemocyanins are multimeric oxygen-transport proteins in the hemolymph of many arthropods and mollusks. The overall molecular architecture of arthropod and molluscan hemocyanin is very different, although they possess a similar binuclear type 3 copper center to bind oxygen in a side-on conformation. Gastropod hemocyanin is a 35 nm cylindrical didecamer (2 × 10-mer) based on a 400 kDa subunit. The latter is subdivided into eight paralogous "functional units" (FU-a to FU-h), each with an active site. FU-a to FU-f contribute to the cylinder wall, whereas FU-g and FU-h form the internal collar complex. Atomic structures of FU-e and FU-g, and a 9 Å cryoEM structure of the 8 MDa didecamer are available. Recently, the structure of keyhole limpet hemocyanin FU-h (KLH1-h) was presented as a C(α) -trace at 4 Å resolution. Unlike the other seven FU types, FU-h contains an additional C-terminal domain with a cupredoxin-like fold. Because of the resolution limit of 4 Å, in some loops, the course of the protein backbone could not be established with high certainty yet. Here, we present a refined atomic structure of FU-h (KLH1-h) obtained from low-resolution refinement, which unambiguously establishes the course of the polypeptide backbone and reveals the disulfide bridges as well as the orientation of bulky amino acids.

PubMed: 21445849
DOI: 10.1002/iub.435

Experimental method

X-RAY DIFFRACTION (4 Å)