Article

The Cupredoxin-like Domains in Hemocyanins

Institut für Molekulare Biophysik, Johannes Gutenberg-Universität, Jakob Welder Weg 26, 55128 Mainz, Germany.
Biochemical Journal (Impact Factor: 4.78). 12/2009; 426(3):373-8. DOI: 10.1042/BJ20091501
Source: PubMed

ABSTRACT 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, Aug 26, 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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    • "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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    • "Note the position of the disulfide bridges (yellow) in the FU-h dimer. Figure according to Jaenicke et al (2010)/Gatso- giannis & Markl (2009) and this study (6, 20). [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.] "
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