| First Author | Khandros E | Year | 2012 |
| Journal | J Biol Chem | Volume | 287 |
| Issue | 14 | Pages | 11325-37 |
| PubMed ID | 22287545 | Mgi Jnum | J:338784 |
| Mgi Id | MGI:6832566 | Doi | 10.1074/jbc.M111.313205 |
| Citation | Khandros E, et al. (2012) Insights into hemoglobin assembly through in vivo mutagenesis of alpha-hemoglobin stabilizing protein. J Biol Chem 287(14):11325-37 |
| abstractText | alpha-Hemoglobin stabilizing protein (AHSP) is believed to facilitate adult Hemoglobin A assembly and protect against toxic free alpha-globin subunits. Recombinant AHSP binds multiple forms of free alpha-globin to stabilize their structures and inhibit precipitation. However, AHSP also stimulates autooxidation of alphaO(2) 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 alpha chains with 30-fold increased affinity. Both P30W and P30A mutant proteins also caused decreased rates of alphaO(2) 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 alpha subunits. Together, our findings indicate that the ability of AHSP to stabilize nascent alpha chain folding intermediates prior to hemin reduction and incorporation into adult Hemoglobin A is physiologically more important than AHSP interactions with ferrous alphaO(2) subunits. |
