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Refined Structure of the functional unit (KLH1-H) of keyhole limpet hemocyanin
Structural highlights
FunctionHCY1_MEGCR Hemocyanins are copper-containing oxygen carriers occurring freely dissolved in the hemolymph of many mollusks and arthropods.[1] Publication Abstract from PubMedHemocyanins 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 x 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 A 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(alpha) -trace at 4 A 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 A, 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. The refined structure of functional unit h of keyhole limpet hemocyanin (KLH1-h) reveals disulfide bridges.,Jaenicke E, Buchler K, Decker H, Markl J, Schroder GF IUBMB Life. 2011 Mar;63(3):183-7. doi: 10.1002/iub.435. PMID:21445849[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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