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Molecular phylogeny of Fv1
C F Qi1, F Bonhomme, A Buckler-White
1Laboratory of Immunopathology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Building 7, Room 304, MSC 0760, Bethesda, Maryland 20892-0760, USA.
Abstract:
Alleles at the Fv1 gene of inbred mice confer resistance to infection and spread of vertically or horizontally transmitted murine leukemia viruses (MuLV). The nucleotide sequence of Fv1 bears similarity to the gag of a human endogenous retrovirus, HERV-L, but is more closely related to the gag-coding sequence of a newly described class of HERV-L-related mouse endogenous retroviruses designated MuERV-L. Both observations suggest an origin of Fv1 from endogenous gag sequences. The molecular definition of Fv1 provided an opportunity to determine the phylogeny of the gene among wild mice and its relation to MuERV-L. PCR primers, chosen to include most of the coding region of Fv1 for both the n and b alleles, were used to amplify sequences from animals of the genus Mus, which were then sequenced. Closely related products were obtained from almost all animals examined that evolved after the separation from Rattus, in which the homologous gene was shown to be absent. A phylogenetic tree generated with Fv1 sequence data differs noticeably from that developed with sequence data from other genes. In addition, non-synonymous changes were found to be present twice as frequently as synonymous changes, a fact that departs from the standard behavior of a structural gene. These observations suggest that the Fv1 gene may have been subjected to possible horizontal transfers as well as to positive Darwinian selection.
Insights
The Fv1 gene in mice, crucial for resisting murine leukemia viruses (MuLV), likely originated from endogenous retroviruses. Its unique evolutionary path suggests horizontal gene transfer and positive selection.
Area of Science:
- Virology
- Genetics
- Evolutionary Biology
Background:
- The Fv1 gene in mice provides resistance against murine leukemia viruses (MuLV) through its different alleles.
- The Fv1 gene sequence shows similarity to human endogenous retrovirus (HERV-L) gag sequences and is closely related to mouse endogenous retroviruses (MuERV-L), suggesting an endogenous origin.
Purpose of the Study:
- To investigate the evolutionary origins and phylogenetic relationships of the Fv1 gene.
- To explore the evolutionary pressures acting on the Fv1 gene by comparing its sequence data with other genes.
Main Methods:
- Polymerase chain reaction (PCR) primers were designed to amplify the coding region of both Fv1 alleles (n and b).
- Sequences were amplified from various species within the genus Mus and sequenced.
- Phylogenetic analysis was performed using the obtained Fv1 sequences and compared with trees from other genes.
Main Results:
- Homologous Fv1 genes were found in Mus species that evolved after divergence from Rattus, but absent in Rattus.
- A phylogenetic tree based on Fv1 sequences differed significantly from trees based on other genes.
- Non-synonymous changes occurred twice as frequently as synonymous changes in Fv1, deviating from typical structural gene behavior.
Conclusions:
- The Fv1 gene likely originated from endogenous retroviral sequences.
- Evidence suggests the Fv1 gene may have undergone horizontal gene transfer.
- The observed mutation patterns indicate positive Darwinian selection may have acted on the Fv1 gene.