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Structure of oxidized alpha-haemoglobin bound to AHSP reveals a protective mechanism for haem

journal contribution
posted on 2023-05-17, 02:58 authored by Feng, L, Zhou, S, Gu, L, David GellDavid Gell, Mackay, JP, Weiss, MJ, Gow, AJ, Shi, Y
The synthesis of haemoglobin A (HbA) is exquisitely coordinated during erythrocyte development to prevent damaging effects from individual α- and β-subunits. The α-haemoglobin-stabilizing protein (AHSP) binds α-haemoglobin (αHb), inhibits the ability of αHb to generate reactive oxygen species and prevents its precipitation on exposure to oxidant stress. The structure of AHSP bound to ferrous αHb is thought to represent a transitional complex through which αHb is converted to a non-reactive, hexacoordinate ferric form. Here we report the crystal structure of this ferric αHb-AHSP complex at 2.4 A resolution. Our findings reveal a striking bis-histidyl configuration in which both the proximal and the distal histidines coordinate the haem iron atom. To attain this unusual conformation, segments of αHb undergo drastic structural rearrangements, including the repositioning of several α-helices. Moreover, conversion to the ferric bishistidine configuration strongly and specifically inhibits redox chemistry catalysis and haem loss from αHb. The observed structural changes, which impair the chemical reactivity of haem iron, explain how AHSP stabilizes αHb and prevents its damaging effects in cells.


Publication title

Nature: International Weekly Journal of Science










Menzies Institute for Medical Research


Nature Publishing Group

Place of publication

Macmillan Building, 4 Crinan St, London, England, N1 9Xw

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Expanding knowledge in the biological sciences

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