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Repeated evolution of chimeric fusion genes in the ?-globin gene family of laurasiatherian mammals.

ABSTRACT: The evolutionary fate of chimeric fusion genes may be strongly influenced by their recombinational mode of origin and the nature of functional divergence between the parental genes. In the ?-globin gene family of placental mammals, the two postnatally expressed ?- and ?-globin genes (HBD and HBB, respectively) have a propensity for recombinational exchange via gene conversion and unequal crossing-over. In the latter case, there are good reasons to expect differences in retention rates for the reciprocal HBB/HBD and HBD/HBB fusion genes due to thalassemia pathologies associated with the HBD/HBB "Lepore" deletion mutant in humans. Here, we report a comparative genomic analysis of the mammalian ?-globin gene cluster, which revealed that chimeric HBB/HBD fusion genes originated independently in four separate lineages of laurasiatherian mammals: Eulipotyphlans (shrews, moles, and hedgehogs), carnivores, microchiropteran bats, and cetaceans. In cases where an independently derived "anti-Lepore" duplication mutant has become fixed, the parental HBD and/or HBB genes have typically been inactivated or deleted, so that the newly created HBB/HBD fusion gene is primarily responsible for synthesizing the ?-type subunits of adult and fetal hemoglobin (Hb). Contrary to conventional wisdom that the HBD gene is a vestigial relict that is typically inactivated or expressed at negligible levels, we show that HBD-like genes often encode a substantial fraction (20-100%) of ?-chain Hbs in laurasiatherian taxa. Our results indicate that the ascendancy or resuscitation of genes with HBD-like coding sequence requires the secondary acquisition of HBB-like promoter sequence via unequal crossing-over or interparalog gene conversion.

SUBMITTER: Gaudry MJ

PROVIDER: S-EPMC4041002 | biostudies-literature | 2014 May

REPOSITORIES: biostudies-literature

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Repeated evolution of chimeric fusion genes in the β-globin gene family of laurasiatherian mammals.

Gaudry Michael J MJ Storz Jay F JF Butts Gary Tyler GT Campbell Kevin L KL Hoffmann Federico G FG

Genome biology and evolution 20140509 5

The evolutionary fate of chimeric fusion genes may be strongly influenced by their recombinational mode of origin and the nature of functional divergence between the parental genes. In the β-globin gene family of placental mammals, the two postnatally expressed δ- and β-globin genes (HBD and HBB, respectively) have a propensity for recombinational exchange via gene conversion and unequal crossing-over. In the latter case, there are good reasons to expect differences in retention rates for the re ...[more]

PMID: 24814285

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Dataset Information

Repeated evolution of chimeric fusion genes in the ?-globin gene family of laurasiatherian mammals.

Publications

Repeated evolution of chimeric fusion genes in the β-globin gene family of laurasiatherian mammals.

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