Structures of WT and mutant α globin-AHSP interfaces. The structure of the complex was adapted from Feng et al9 (PDB 1z8u), and the drawings were made in PyMol. (A) Close-up ribbon diagram of the WT α globin-AHSP interface (α globin in silver and AHSP in teal; α K99 and AHSP Q25 and D29 side chains are depicted as CPK-colored sticks). The electrostatic interactions between α globin K99 and AHSP D29 stabilize the α globin-AHSP interface. The α K99E mutant disrupts these favorable electrostatic interactions. (B) Close-up ribbon diagram of a theoretical model of the same interface but with α K99E and AHSP D29R mutations. As is suggested by data in this work, favorable electrostatic interactions between the negatively charged α globin E99 side chain and the positively charged AHSP revertant R29 can restore heterodimerization.
