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Insights into Hemoglobin Assembly through in Vivo Mutagenesis of α-Hemoglobin Stabilizing Protein

Citation

Khandros, E and Mollan, TL and Yu, X and Wang, X and Yao, Y and D'Souza, J and Gell, DA and Olson, JS and Weiss, MJ, Insights into Hemoglobin Assembly through in Vivo Mutagenesis of α-Hemoglobin Stabilizing Protein, Journal of Biological Chemistry, 287, (14) pp. 11325-11337. ISSN 0021-9258 (2012) [Refereed Article]


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Copyright Statement

Copyright 2012 American Society for Biochemistry and Molecular Biology, Inc

DOI: doi:10.1074/jbc.M111.313205

Abstract

α-Hemoglobin stabilizing protein (AHSP) is believed to facilitate adult Hemoglobin A assembly and protect against toxic free α-globin subunits. Recombinant AHSP binds multiple forms of free α-globin to stabilize their structures and inhibit precipitation. However, AHSP also stimulates autooxidation of αO2 subunit and its rapid conversion to a partially unfolded bishistidyl hemichrome structure. To investigate these biochemical properties, we altered the evolutionarily conserved AHSP proline 30 in recombinantly expressed proteins and introduced identical mutations into the endogenous murine Ahsp gene. In vitro, the P30W AHSP variant bound oxygenated α chains with 30-fold increased affinity. Both P30W and P30A mutant proteins also caused decreased rates of αO2 autooxidation as compared with wild-type AHSP. Despite these abnormalities, mice harboring P30A or P30W Ahsp mutations exhibited no detectable defects in erythropoiesis at steady state or during induced stresses. Further biochemical studies revealed that the AHSP P30A and P30W substitutions had minimal effects on AHSP interactions with ferric α subunits. Together, our findings indicate that the ability of AHSP to stabilize nascent α chain folding intermediates prior to hemin reduction and incorporation into adult Hemoglobin A is physiologically more important than AHSP interactions with ferrous αO2 subunits.

Item Details

Item Type:Refereed Article
Keywords:AHSP, hemoglobin, in vivo mutagenesis
Research Division:Biological Sciences
Research Group:Biochemistry and Cell Biology
Research Field:Structural Biology (incl. Macromolecular Modelling)
Objective Division:Health
Objective Group:Clinical Health (Organs, Diseases and Abnormal Conditions)
Objective Field:Blood Disorders
Author:Gell, DA (Dr David Gell)
ID Code:79774
Year Published:2012
Funding Support:National Health and Medical Research Council (570876)
Web of Science® Times Cited:10
Deposited By:Menzies Institute for Medical Research
Deposited On:2012-10-02
Last Modified:2017-11-06
Downloads:0

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