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Publication Abstract from PubMed

BACKGROUND: Deer mice (Peromyscus maniculatus) that are native to high altitudes in the Rocky Mountains have evolved hemoglobins with an increased oxygen-binding affinity relative to those of lowland conspecifics. To elucidate the molecular mechanisms responsible for the evolved increase in hemoglobin-oxygen affinity, the crystal structure of the highland hemoglobin variant was solved and compared with the previously reported structure for the lowland variant. RESULTS: Highland hemoglobin yielded at least two crystal types, in which the longest axes were 507 and 230 A. Using the smaller unit cell crystal, the structure was solved at 2.2 A resolution. The asymmetric unit contained two tetrameric hemoglobin molecules. CONCLUSIONS: The analyses revealed that alphaPro50 in the highland hemoglobin variant promoted a stable interaction between alphaHis45 and heme that was not seen in the alphaHis50 lowland variant. The alphaPro50 mutation also altered the nature of atomic contacts at the alpha1beta2/alpha2beta1 intersubunit interfaces. These results demonstrate how affinity-altering changes in intersubunit interactions can be produced by mutations at structurally remote sites.

Alteration of the alpha1beta2/alpha2beta1 subunit interface contributes to the increased hemoglobin-oxygen affinity of high-altitude deer mice.,Inoguchi N, Mizuno N, Baba S, Kumasaka T, Natarajan C, Storz JF, Moriyama H PLoS One. 2017 Mar 31;12(3):e0174921. doi: 10.1371/journal.pone.0174921., eCollection 2017. PMID:28362841^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.