In vertebrate haemoglobin (Hb), the NH2-terminal residues of the α- and β-chain subunits are thought to play an important role in the allosteric binding of protons (Bohr effect), CO2 (as carbamino derivatives), chloride ions, and organic phosphates. Accordingly, acetylation of the α- and/or β-chain NH2-termini may have significant effects on the oxygenation properties of Hb. Here we investigate the effect of NH2-terminal acetylation by using a newly developed expression plasmid system that enables us to compare recombinantly expressed Hbs that are structurally identical except for the presence or absence of NH2-terminal acetyl groups. Experiments with native and recombinant Hbs of representative vertebrates reveal that NH2-terminal acetylation does not impair the Bohr effect, nor does it significantly diminish responsiveness to allosteric cofactors, such as chloride ions or organic phosphates. These results suggest that observed variation in the oxygenation properties of vertebrate Hbs is principally explained by amino acid divergence in the constituent globin chains rather than post-translational modifications of the globin chain NH2-termini.
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October 2020
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Cover Image
Cover Image
The cover image showing the crystal structure of human hemoglobin (PDB: 1GZX). For more information, see the article by Natarajan et al. (pp. 3839–3850). Artwork Image courtesy of C. Natarajan.
Research Article|
October 12 2020
Effect of NH2-terminal acetylation on the oxygenation properties of vertebrate haemoglobin
Chandrasekhar Natarajan
;
1School of Biological Sciences, University of Nebraska, Lincoln, NE 68588, U.S.A.
Correspondence: Chandrasekhar Natarajan (cnatarajan2@unl.edu) or Jay F. Storz (jstorz2@unl.edu)
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Anthony V. Signore;
Anthony V. Signore
1School of Biological Sciences, University of Nebraska, Lincoln, NE 68588, U.S.A.
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Vikas Kumar;
Vikas Kumar
2Mass Spectrometry and Proteomics Core Facility, University of Nebraska Medical Center, Omaha, NE 68198, U.S.A.
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Roy E. Weber;
Roy E. Weber
3Zoophysiology, Department of Biology, Aarhus University, Aarhus, Denmark
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Angela Fago;
Angela Fago
3Zoophysiology, Department of Biology, Aarhus University, Aarhus, Denmark
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Jay F. Storz
1School of Biological Sciences, University of Nebraska, Lincoln, NE 68588, U.S.A.
Correspondence: Chandrasekhar Natarajan (cnatarajan2@unl.edu) or Jay F. Storz (jstorz2@unl.edu)
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Publisher: Portland Press Ltd
Received:
August 08 2020
Revision Received:
September 08 2020
Accepted:
September 15 2020
Accepted Manuscript online:
September 16 2020
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 2020 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society
2020
Biochem J (2020) 477 (19): 3839–3850.
Article history
Received:
August 08 2020
Revision Received:
September 08 2020
Accepted:
September 15 2020
Accepted Manuscript online:
September 16 2020
Citation
Chandrasekhar Natarajan, Anthony V. Signore, Vikas Kumar, Roy E. Weber, Angela Fago, Jay F. Storz; Effect of NH2-terminal acetylation on the oxygenation properties of vertebrate haemoglobin. Biochem J 16 October 2020; 477 (19): 3839–3850. doi: https://doi.org/10.1042/BCJ20200623
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