The Cupredoxin-like Domains in Hemocyanins

Institut für Molekulare Biophysik, Johannes Gutenberg-Universität, Jakob Welder Weg 26, 55128 Mainz, Germany.
Biochemical Journal (Impact Factor: 4.4). 12/2009; 426(3):373-8. DOI: 10.1042/BJ20091501
Source: PubMed


Haemocyanins are multimeric oxygen transport proteins, which bind oxygen to type 3 copper sites. Arthropod haemocyanins contain 75-kDa subunits, whereas molluscan haemocyanins contain 350-400-kDa subunits comprising seven or eight different 50 kDa FUs (functional units) designated FU-a to FU-h, each with an active site. FU-h possesses a tail of 100 amino acids not present in the other FUs. In the present study we show by X-ray crystallography that in FU-h of KLH1 (keyhole-limpet-haemocyanin isoform 1) the structure of the tail domain is cupredoxin-like but contains no copper. The copper-free domain 3 in arthropod haemocyanin subunits has also recently been reinterpreted as being cupredoxin-like. We propose that the cupredoxin-like domain in both haemocyanin types once served to upload copper to the active site of the oxygen-binding domain.

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Available from: Jürgen Markl, Oct 09, 2015
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    • "Arthropod hemocyanin consists of three different domains (a N-terminal domain shielding the entrance of the active site, a central domain containing the active site and a immunoglobulin-like C-terminal domain). This significant structural difference might be a reason for the absence of the thioether bond in arthropod hemocyanins [48] "
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    ABSTRACT: Aurone synthase from Coreopsis grandiflora (cgAUS1), catalyzing conversion of butein to sulfuretin in a type-3 copper center, is a rare example of a polyphenol oxidase involved in anabolism. Site-directed mutagenesis around the CuA site of AUS1 was performed, and recombinant enzymes were analyzed by mass spectrometry. Replacement of the coordinating CuA histidines with alanine resulted in the presence of a single copper and loss of diphenolase activity. The thioether bridge-building cysteine and a phenylalanine over the CuA site, exchanged to alanine, have no influence on copper content but appear to play an important role in substrate binding. Copyright © 2015. Published by Elsevier B.V.
    FEBS Letters 02/2015; 111(7). DOI:10.1016/j.febslet.2015.02.009 · 3.17 Impact Factor
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    • "Similar to the structures of FUs in native HdH1 (PDB ID: 3J32) [23], all FUs of isomeric HdH1 contain two structural domains, the N-terminal core domain, which predominantly consists of α-helices, and the C-terminalβsheet domain, which contains theβsheets region (dashed lines in Fig. S3). FU_H, which locates in the end and forms the slab of cylindrical decamers (Fig. 1B and 1D, magenta domains), is structurally unique among all of the FUs of HdH1 as it has an additional cupredoxin-like fold (Fig S2, sequence underlined and Fig. S3, red densities) [28], [29]. All of the built pseudoatomic models of isomeric FUs fit well with the corresponding density maps of isomeric HdH1, while the α helices,βsheets and the loops of each FU can be accommodated precisely in the density maps (Fig. S3). "
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    ABSTRACT: Hemocyanins (Hcs) of arthropods and mollusks function not only as oxygen transporters, but also as phenoloxidases (POs). In invertebrates, PO is an important component in the innate immune cascade, where it functions as the initiator of melanin synthesis, a pigment involved in encapsulating and killing of pathogenic microbes. Although structures of Hc from several species of invertebrates have been reported, the structural basis for how PO activity is triggered by structural changes of Hc in vivo remains poorly understood. Here, we report a 6.8 Å cryo-electron microscopy (cryo-EM) structure of the isomeric form of hemocyanin, which was isolated from Abalone Shriveling syndrome-associated Virus (AbSV) infected abalone (Halitotis diversicolor), and build a pseudoatomic model of isomeric H. diversicolor hemocyanin 1 (HdH1). Our results show that, compared with native form of HdH1, the architecture of isomeric HdH1 turns into a more relaxed form. The interactions between certain functional units (FUs) present in the native form of Hc either decreased or were totally abolished in the isomeric form of Hc. As a result of that, native state Hc switches to its isomeric form, enabling it to play its role in innate immune responses against invading pathogens.
    PLoS ONE 06/2014; 9(6):e98766. DOI:10.1371/journal.pone.0098766 · 3.23 Impact Factor
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    • "FUs are typically 50 kDa in size, however, FU-h contains an additional stretch of $100 amino acids (cupredoxin-like domain) located at the C-terminal end of the polypeptide, bringing the total molecular weight of FU-h to $60 kDa (Lieb et al., 2000; Jaenicke et al., 2010). Each FU is ordinarily composed of two domains, the a-domain consisting of a four a-helix bundle that houses the di-copper centre and the b-domain incorporating a seven stranded anti-parallel b-barrel (Fig. 2). "
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    ABSTRACT: Substantial evidence gathered recently has revealed the multiple functionalities of hemocyanin. Contrary to previous claims that this ancient protein is involved solely in oxygen transport within the hemolymph of invertebrates, hemocyanin and hemocyanin-derived peptides have been linked to key aspects of innate immunity, in particular, antiviral and phenoloxidase-like activities. Both phenoloxidase and hemocyanin belong to the family of type-3 copper proteins and share a high degree of sequence homology. While the importance of phenoloxidase in immunity and development is well characterised, the contribution of hemocyanin to biological defence systems within invertebrates is not recognised widely. This review focusses on the conversion of hemocyanin into a phenoloxidase-like enzyme and the array of hemocyanin-derived immune responses documented to date.
    Developmental and comparative immunology 01/2014; 45(1). DOI:10.1016/j.dci.2014.01.021 · 2.82 Impact Factor
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