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标题：Evolutionary and functional insights into the mechanism underlying high-altitude adaptation of deer mouse hemoglobin
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作者：Jay F. Storz ; Amy M. Runck ; Stephen J. Sabatino 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2009
卷号：106
期号：34
页码：14450-14455
DOI：10.1073/pnas.0905224106
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Adaptive modifications of heteromeric proteins may involve genetically based changes in single subunit polypeptides or parallel changes in multiple genes that encode distinct, interacting subunits. Here we investigate these possibilities by conducting a combined evolutionary and functional analysis of duplicated globin genes in natural populations of deer mice (Peromyscus maniculatus) that are adapted to different elevational zones. A multilocus analysis of nucleotide polymorphism and linkage disequilibrium revealed that high-altitude adaptation of deer mouse hemoglobin involves parallel functional differentiation at multiple unlinked gene duplicates: two {alpha}-globin paralogs on chromosome 8 and two {beta}-globin paralogs on chromosome 1. Differences in O2-binding affinity of the alternative {beta}-chain hemoglobin isoforms were entirely attributable to allelic differences in sensitivity to 2,3-diphosphoglycerate (DPG), an allosteric cofactor that stabilizes the low-affinity, deoxygenated conformation of the hemoglobin tetramer. The two-locus {beta}-globin haplotype that predominates at high altitude is associated with suppressed DPG-sensitivity (and hence, increased hemoglobin-O2 affinity), which enhances pulmonary O2 loading under hypoxia. The discovery that allelic differences in DPG-sensitivity contribute to adaptive variation in hemoglobin-O2 affinity illustrates the value of integrating evolutionary analyses of sequence variation with mechanistic appraisals of protein function. Investigation into the functional significance of the deer mouse {beta}-globin polymorphism was motivated by the results of population genetic analyses which revealed evidence for a history of divergent selection between elevational zones. The experimental measures of O2-binding properties corroborated the tests of selection by demonstrating a functional difference between the products of alternative alleles.
关键词：gene duplication ; hypoxia ; molecular adaptation ; Peromyscus ; positive selection