Substitutions in the β subunits of sickle-cell hemoglobin improve oxidative stability and increase the delay time of sickle-cell fiber formation

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dc.citation.firstpage4145en_US
dc.citation.issueNumber11en_US
dc.citation.journalTitleJournal of Biological Chemistryen_US
dc.citation.lastpage4159en_US
dc.citation.volumeNumber294en_US
dc.contributor.authorMeng, Fantaoen_US
dc.contributor.authorKassa, Tigisten_US
dc.contributor.authorStrader, Michael Braden_US
dc.contributor.authorSoman, Jayashreeen_US
dc.contributor.authorOlson, John S.en_US
dc.contributor.authorAlayash, Abdu I.en_US
dc.date.accessioned2019-12-11T15:44:12Zen_US
dc.date.available2019-12-11T15:44:12Zen_US
dc.date.issued2019en_US
dc.description.abstractAfter reacting with hydrogen peroxide (H2O2), sickle-cell hemoglobin (HbS, βE6V) remains longer in a highly oxidizing ferryl form (HbFe4+=O) and induces irreversible oxidation of “hot-spot” amino acids, including βCys-93. To control the damaging ferryl heme, here we constructed three HbS variants. The first contained a redox-active Tyr in β subunits (F41Y), a substitution present in Hb Mequon; the second contained the Asp (K82D) found in the β cleft of Hb Providence; and the third had both of these β substitutions. Both the single Tyr-41 and Asp-82 constructs lowered the oxygen affinity of HbS but had little or no effects on autoxidation or heme loss kinetics. In the presence of H2O2, both rHbS βF41Y and βF41Y/K82D enhanced ferryl Hb reduction by providing a pathway for electrons to reduce the heme via the Tyr-41 side chain. MS analysis of βCys-93 revealed moderate inhibition of thiol oxidation in the HbS single F41Y variant and dramatic 3- to 8-fold inhibition of cysteic acid formation in rHbS βK82D and βF41Y/K82D, respectively. Under hypoxia, βK82D and βF41Y/K82D HbS substitutions increased the delay time by ∼250 and 600 s before the onset of polymerization compared with the rHbS control and rHbS βF41Y, respectively. Moreover, at 60 °C, rHbS βK82D exhibited superior structural stability. Asp-82 also enhanced the function of Tyr as a redox-active amino acid in the rHbS βF41Y/K82D variant. We conclude that the βK82D and βF41Y substitutions add significant resistance to oxidative stress and anti-sickling properties to HbS and therefore could be potential genome-editing targets.en_US
dc.identifier.citationMeng, Fantao, Kassa, Tigist, Strader, Michael Brad, et al.. "Substitutions in the β subunits of sickle-cell hemoglobin improve oxidative stability and increase the delay time of sickle-cell fiber formation." <i>Journal of Biological Chemistry,</i> 294, no. 11 (2019) American Society for Biochemistry and Molecular Biology: 4145-4159. https://doi.org/10.1074/jbc.RA118.006452.en_US
dc.identifier.digital2019-Meng-4145-59en_US
dc.identifier.doihttps://doi.org/10.1074/jbc.RA118.006452en_US
dc.identifier.urihttps://hdl.handle.net/1911/107838en_US
dc.language.isoengen_US
dc.publisherAmerican Society for Biochemistry and Molecular Biologyen_US
dc.rightsFinal version free via Creative Commons CC-BY license.en_US
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/en_US
dc.titleSubstitutions in the β subunits of sickle-cell hemoglobin improve oxidative stability and increase the delay time of sickle-cell fiber formationen_US
dc.typeJournal articleen_US
dc.type.dcmiTexten_US
dc.type.publicationpublisher versionen_US
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